PEP-8 standards followed

8 files changed, 228 insertions, 204 deletions

diff --git a/tablib/packages/dbfpy/dbf.py b/tablib/packages/dbfpy/dbf.py
index b3d2e21..add74da 100644
--- a/tablib/packages/dbfpy/dbf.py
+++ b/tablib/packages/dbfpy/dbf.py
@@ -63,9 +63,10 @@ __author__ = "Jeff Kunce <kuncej@mail.conservation.state.mo.us>"
 __all__ = ["Dbf"]
 
 from . import header
-from .import record
+from . import record
 from utils import INVALID_VALUE
 
+
 class Dbf(object):
     """DBF accessor.
 
@@ -82,13 +83,13 @@ class Dbf(object):
     """
 
     __slots__ = ("name", "header", "stream",
-        "_changed", "_new", "_ignore_errors")
+                 "_changed", "_new", "_ignore_errors")
 
     HeaderClass = header.DbfHeader
     RecordClass = record.DbfRecord
     INVALID_VALUE = INVALID_VALUE
 
-    ## initialization and creation helpers
+    # initialization and creation helpers
 
     def __init__(self, f, readOnly=False, new=False, ignoreErrors=False):
         """Initialize instance.
@@ -137,7 +138,7 @@ class Dbf(object):
         self._new = bool(new)
         self._changed = False
 
-    ## properties
+    # properties
 
     closed = property(lambda self: self.stream.closed)
     recordCount = property(lambda self: self.header.recordCount)
@@ -149,6 +150,7 @@ class Dbf(object):
     def ignoreErrors(self, value):
         """Update `ignoreErrors` flag on the header object and self"""
         self.header.ignoreErrors = self._ignore_errors = bool(value)
+
     ignoreErrors = property(
         lambda self: self._ignore_errors,
         ignoreErrors,
@@ -159,7 +161,7 @@ class Dbf(object):
 
         """)
 
-    ## protected methods
+    # protected methods
 
     def _fixIndex(self, index):
         """Return fixed index.
@@ -185,7 +187,7 @@ class Dbf(object):
             raise IndexError("Record index out of range")
         return index
 
-    ## iterface methods
+    # iterface methods
 
     def close(self):
         self.flush()
@@ -226,9 +228,9 @@ class Dbf(object):
             self.header.addField(*defs)
         else:
             raise TypeError("At least one record was added, "
-                "structure can't be changed")
+                            "structure can't be changed")
 
-    ## 'magic' methods (representation and sequence interface)
+    # 'magic' methods (representation and sequence interface)
 
     def __repr__(self):
         return "Dbf stream '%s'\n" % self.stream + repr(self.header)
@@ -248,19 +250,20 @@ class Dbf(object):
         self._changed = True
         self._new = False
 
-    #def __del__(self):
-    #    """Flush stream upon deletion of the object."""
-    #    self.flush()
+        # def __del__(self):
+        #    """Flush stream upon deletion of the object."""
+        #    self.flush()
 
 
-def demoRead(filename):
+def demo_read(filename):
     _dbf = Dbf(filename, True)
     for _rec in _dbf:
         print
         print(repr(_rec))
     _dbf.close()
 
-def demoCreate(filename):
+
+def demo_create(filename):
     _dbf = Dbf(filename, new=True)
     _dbf.addField(
         ("NAME", "C", 15),
@@ -269,10 +272,10 @@ def demoCreate(filename):
         ("BIRTHDATE", "D"),
     )
     for (_n, _s, _i, _b) in (
-        ("John", "Miller", "YC", (1981, 1, 2)),
-        ("Andy", "Larkin", "AL", (1982, 3, 4)),
-        ("Bill", "Clinth", "", (1983, 5, 6)),
-        ("Bobb", "McNail", "", (1984, 7, 8)),
+            ("John", "Miller", "YC", (1981, 1, 2)),
+            ("Andy", "Larkin", "AL", (1982, 3, 4)),
+            ("Bill", "Clinth", "", (1983, 5, 6)),
+            ("Bobb", "McNail", "", (1984, 7, 8)),
     ):
         _rec = _dbf.newRecord()
         _rec["NAME"] = _n
@@ -283,10 +286,12 @@ def demoCreate(filename):
     print(repr(_dbf))
     _dbf.close()
 
-if (__name__=='__main__'):
+
+if __name__ == '__main__':
     import sys
+
     _name = len(sys.argv) > 1 and sys.argv[1] or "county.dbf"
-    demoCreate(_name)
-    demoRead(_name)
+    demo_create(_name)
+    demo_read(_name)
 
-# vim: set et sw=4 sts=4 :
+    # vim: set et sw=4 sts=4 :
diff --git a/tablib/packages/dbfpy/dbfnew.py b/tablib/packages/dbfpy/dbfnew.py
index dea7e52..7a06d00 100644
--- a/tablib/packages/dbfpy/dbfnew.py
+++ b/tablib/packages/dbfpy/dbfnew.py
@@ -29,6 +29,7 @@ from fields import *
 from header import *
 from record import *
 
+
 class _FieldDefinition(object):
     """Field definition.
 
@@ -151,28 +152,28 @@ class dbf_new(object):
         _dbfh.write(stream)
 
 
-if (__name__=='__main__'):
+if __name__ == '__main__':
     # create a new DBF-File
-    dbfn=dbf_new()
-    dbfn.add_field("name",'C',80)
-    dbfn.add_field("price",'N',10,2)
-    dbfn.add_field("date",'D',8)
+    dbfn = dbf_new()
+    dbfn.add_field("name", 'C', 80)
+    dbfn.add_field("price", 'N', 10, 2)
+    dbfn.add_field("date", 'D', 8)
     dbfn.write("tst.dbf")
     # test new dbf
     print "*** created tst.dbf: ***"
     dbft = Dbf('tst.dbf', readOnly=0)
     print repr(dbft)
     # add a record
-    rec=DbfRecord(dbft)
-    rec['name']='something'
-    rec['price']=10.5
-    rec['date']=(2000,1,12)
+    rec = DbfRecord(dbft)
+    rec['name'] = 'something'
+    rec['price'] = 10.5
+    rec['date'] = (2000, 1, 12)
     rec.store()
     # add another record
-    rec=DbfRecord(dbft)
-    rec['name']='foo and bar'
-    rec['price']=12234
-    rec['date']=(1992,7,15)
+    rec = DbfRecord(dbft)
+    rec['name'] = 'foo and bar'
+    rec['price'] = 12234
+    rec['date'] = (1992, 7, 15)
     rec.store()
 
     # show the records
@@ -181,8 +182,8 @@ if (__name__=='__main__'):
     for i1 in range(len(dbft)):
         rec = dbft[i1]
         for fldName in dbft.fieldNames:
-            print '%s:\t %s'%(fldName, rec[fldName])
+            print '%s:\t %s' % (fldName, rec[fldName])
         print
     dbft.close()
 
-# vim: set et sts=4 sw=4 :
+    # vim: set et sts=4 sw=4 :
diff --git a/tablib/packages/dbfpy3/dbf.py b/tablib/packages/dbfpy3/dbf.py
index 42de8a4..6fee457 100644
--- a/tablib/packages/dbfpy3/dbf.py
+++ b/tablib/packages/dbfpy3/dbf.py
@@ -66,6 +66,7 @@ from . import header
 from . import record
 from .utils import INVALID_VALUE
 
+
 class Dbf(object):
     """DBF accessor.
 
@@ -82,13 +83,13 @@ class Dbf(object):
     """
 
     __slots__ = ("name", "header", "stream",
-        "_changed", "_new", "_ignore_errors")
+                 "_changed", "_new", "_ignore_errors")
 
     HeaderClass = header.DbfHeader
     RecordClass = record.DbfRecord
     INVALID_VALUE = INVALID_VALUE
 
-    ## initialization and creation helpers
+    # initialization and creation helpers
 
     def __init__(self, f, readOnly=False, new=False, ignoreErrors=False):
         """Initialize instance.
@@ -137,7 +138,7 @@ class Dbf(object):
         self._new = bool(new)
         self._changed = False
 
-    ## properties
+    # properties
 
     closed = property(lambda self: self.stream.closed)
     recordCount = property(lambda self: self.header.recordCount)
@@ -149,6 +150,7 @@ class Dbf(object):
     def ignoreErrors(self, value):
         """Update `ignoreErrors` flag on the header object and self"""
         self.header.ignoreErrors = self._ignore_errors = bool(value)
+
     ignoreErrors = property(
         lambda self: self._ignore_errors,
         ignoreErrors,
@@ -159,7 +161,7 @@ class Dbf(object):
 
         """)
 
-    ## protected methods
+    # protected methods
 
     def _fixIndex(self, index):
         """Return fixed index.
@@ -185,7 +187,7 @@ class Dbf(object):
             raise IndexError("Record index out of range")
         return index
 
-    ## iterface methods
+    # iterface methods
 
     def close(self):
         self.flush()
@@ -227,9 +229,9 @@ class Dbf(object):
             self.header.addField(*defs)
         else:
             raise TypeError("At least one record was added, "
-                "structure can't be changed")
+                            "structure can't be changed")
 
-    ## 'magic' methods (representation and sequence interface)
+    # 'magic' methods (representation and sequence interface)
 
     def __repr__(self):
         return "Dbf stream '%s'\n" % self.stream + repr(self.header)
@@ -249,19 +251,20 @@ class Dbf(object):
         self._changed = True
         self._new = False
 
-    #def __del__(self):
-    #    """Flush stream upon deletion of the object."""
-    #    self.flush()
+        # def __del__(self):
+        #    """Flush stream upon deletion of the object."""
+        #    self.flush()
 
 
-def demoRead(filename):
+def demo_read(filename):
     _dbf = Dbf(filename, True)
     for _rec in _dbf:
         print()
         print(repr(_rec))
     _dbf.close()
 
-def demoCreate(filename):
+
+def demo_create(filename):
     _dbf = Dbf(filename, new=True)
     _dbf.addField(
         ("NAME", "C", 15),
@@ -270,10 +273,10 @@ def demoCreate(filename):
         ("BIRTHDATE", "D"),
     )
     for (_n, _s, _i, _b) in (
-        ("John", "Miller", "YC", (1981, 1, 2)),
-        ("Andy", "Larkin", "AL", (1982, 3, 4)),
-        ("Bill", "Clinth", "", (1983, 5, 6)),
-        ("Bobb", "McNail", "", (1984, 7, 8)),
+            ("John", "Miller", "YC", (1981, 1, 2)),
+            ("Andy", "Larkin", "AL", (1982, 3, 4)),
+            ("Bill", "Clinth", "", (1983, 5, 6)),
+            ("Bobb", "McNail", "", (1984, 7, 8)),
     ):
         _rec = _dbf.newRecord()
         _rec["NAME"] = _n
@@ -284,10 +287,12 @@ def demoCreate(filename):
     print(repr(_dbf))
     _dbf.close()
 
-if (__name__=='__main__'):
+
+if __name__ == '__main__':
     import sys
+
     _name = len(sys.argv) > 1 and sys.argv[1] or "county.dbf"
-    demoCreate(_name)
-    demoRead(_name)
+    demo_create(_name)
+    demo_read(_name)
 
 # vim: set et sw=4 sts=4 :
diff --git a/tablib/packages/dbfpy3/dbfnew.py b/tablib/packages/dbfpy3/dbfnew.py
index 4051bc6..8fab275 100644
--- a/tablib/packages/dbfpy3/dbfnew.py
+++ b/tablib/packages/dbfpy3/dbfnew.py
@@ -29,6 +29,7 @@ from .fields import *
 from .header import *
 from .record import *
 
+
 class _FieldDefinition(object):
     """Field definition.
 
@@ -145,28 +146,28 @@ class dbf_new(object):
         _dbfStream.close()
 
 
-if (__name__=='__main__'):
+if __name__ == '__main__':
     # create a new DBF-File
-    dbfn=dbf_new()
-    dbfn.add_field("name",'C',80)
-    dbfn.add_field("price",'N',10,2)
-    dbfn.add_field("date",'D',8)
+    dbfn = dbf_new()
+    dbfn.add_field("name", 'C', 80)
+    dbfn.add_field("price", 'N', 10, 2)
+    dbfn.add_field("date", 'D', 8)
     dbfn.write("tst.dbf")
     # test new dbf
     print("*** created tst.dbf: ***")
     dbft = Dbf('tst.dbf', readOnly=0)
     print(repr(dbft))
     # add a record
-    rec=DbfRecord(dbft)
-    rec['name']='something'
-    rec['price']=10.5
-    rec['date']=(2000,1,12)
+    rec = DbfRecord(dbft)
+    rec['name'] = 'something'
+    rec['price'] = 10.5
+    rec['date'] = (2000, 1, 12)
     rec.store()
     # add another record
-    rec=DbfRecord(dbft)
-    rec['name']='foo and bar'
-    rec['price']=12234
-    rec['date']=(1992,7,15)
+    rec = DbfRecord(dbft)
+    rec['name'] = 'foo and bar'
+    rec['price'] = 12234
+    rec['date'] = (1992, 7, 15)
     rec.store()
 
     # show the records
@@ -175,7 +176,7 @@ if (__name__=='__main__'):
     for i1 in range(len(dbft)):
         rec = dbft[i1]
         for fldName in dbft.fieldNames:
-            print('%s:\t %s'%(fldName, rec[fldName]))
+            print('%s:\t %s' % (fldName, rec[fldName]))
         print()
     dbft.close()
 
diff --git a/tablib/packages/yaml/composer.py b/tablib/packages/yaml/composer.py
index 06e5ac7..d4ef0f1 100644
--- a/tablib/packages/yaml/composer.py
+++ b/tablib/packages/yaml/composer.py
@@ -1,15 +1,16 @@
-
 __all__ = ['Composer', 'ComposerError']
 
 from error import MarkedYAMLError
-from events import *
-from nodes import *
+from events import StreamEndEvent, StreamStartEvent, AliasEvent, SequenceEndEvent, SequenceStartEvent, MappingEndEvent,\
+    MappingStartEvent, ScalarEvent
+from nodes import MappingNode, ScalarNode, SequenceNode
+
 
 class ComposerError(MarkedYAMLError):
     pass
 
-class Composer(object):
 
+class Composer(object):
     def __init__(self):
         self.anchors = {}
 
@@ -39,8 +40,8 @@ class Composer(object):
         if not self.check_event(StreamEndEvent):
             event = self.get_event()
             raise ComposerError("expected a single document in the stream",
-                    document.start_mark, "but found another document",
-                    event.start_mark)
+                                document.start_mark, "but found another document",
+                                event.start_mark)
 
         # Drop the STREAM-END event.
         self.get_event()
@@ -66,15 +67,14 @@ class Composer(object):
             anchor = event.anchor
             if anchor not in self.anchors:
                 raise ComposerError(None, None, "found undefined alias %r"
-                        % anchor.encode('utf-8'), event.start_mark)
+                                    % anchor.encode('utf-8'), event.start_mark)
             return self.anchors[anchor]
         event = self.peek_event()
         anchor = event.anchor
-        if anchor is not None:
-            if anchor in self.anchors:
+        if anchor is not None and anchor in self.anchors:
                 raise ComposerError("found duplicate anchor %r; first occurence"
-                        % anchor.encode('utf-8'), self.anchors[anchor].start_mark,
-                        "second occurence", event.start_mark)
+                                    % anchor.encode('utf-8'), self.anchors[anchor].start_mark,
+                                    "second occurence", event.start_mark)
         self.descend_resolver(parent, index)
         if self.check_event(ScalarEvent):
             node = self.compose_scalar_node(anchor)
@@ -91,7 +91,7 @@ class Composer(object):
         if tag is None or tag == u'!':
             tag = self.resolve(ScalarNode, event.value, event.implicit)
         node = ScalarNode(tag, event.value,
-                event.start_mark, event.end_mark, style=event.style)
+                          event.start_mark, event.end_mark, style=event.style)
         if anchor is not None:
             self.anchors[anchor] = node
         return node
@@ -102,8 +102,8 @@ class Composer(object):
         if tag is None or tag == u'!':
             tag = self.resolve(SequenceNode, None, start_event.implicit)
         node = SequenceNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
+                            start_event.start_mark, None,
+                            flow_style=start_event.flow_style)
         if anchor is not None:
             self.anchors[anchor] = node
         index = 0
@@ -120,20 +120,19 @@ class Composer(object):
         if tag is None or tag == u'!':
             tag = self.resolve(MappingNode, None, start_event.implicit)
         node = MappingNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
+                           start_event.start_mark, None,
+                           flow_style=start_event.flow_style)
         if anchor is not None:
             self.anchors[anchor] = node
         while not self.check_event(MappingEndEvent):
-            #key_event = self.peek_event()
+            # key_event = self.peek_event()
             item_key = self.compose_node(node, None)
-            #if item_key in node.value:
+            # if item_key in node.value:
             #    raise ComposerError("while composing a mapping", start_event.start_mark,
             #            "found duplicate key", key_event.start_mark)
             item_value = self.compose_node(node, item_key)
-            #node.value[item_key] = item_value
+            # node.value[item_key] = item_value
             node.value.append((item_key, item_value))
         end_event = self.get_event()
         node.end_mark = end_event.end_mark
         return node
-
diff --git a/tablib/packages/yaml/constructor.py b/tablib/packages/yaml/constructor.py
index 420c434..d44c7bd 100644
--- a/tablib/packages/yaml/constructor.py
+++ b/tablib/packages/yaml/constructor.py
@@ -1,6 +1,5 @@
-
 __all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
-    'ConstructorError']
+           'ConstructorError']
 
 from error import *
 from nodes import *
@@ -12,13 +11,17 @@ try:
 except NameError:
     from sets import Set as set
 
-import binascii, re, sys, types
+import binascii
+import re
+import sys
+import types
+
 
 class ConstructorError(MarkedYAMLError):
     pass
 
-class BaseConstructor(object):
 
+class BaseConstructor(object):
     yaml_constructors = {}
     yaml_multi_constructors = {}
 
@@ -65,7 +68,7 @@ class BaseConstructor(object):
             return self.constructed_objects[node]
         if node in self.recursive_objects:
             raise ConstructorError(None, None,
-                    "found unconstructable recursive node", node.start_mark)
+                                   "found unconstructable recursive node", node.start_mark)
         self.recursive_objects[node] = None
         constructor = None
         tag_suffix = None
@@ -110,23 +113,23 @@ class BaseConstructor(object):
     def construct_scalar(self, node):
         if not isinstance(node, ScalarNode):
             raise ConstructorError(None, None,
-                    "expected a scalar node, but found %s" % node.id,
-                    node.start_mark)
+                                   "expected a scalar node, but found %s" % node.id,
+                                   node.start_mark)
         return node.value
 
     def construct_sequence(self, node, deep=False):
         if not isinstance(node, SequenceNode):
             raise ConstructorError(None, None,
-                    "expected a sequence node, but found %s" % node.id,
-                    node.start_mark)
+                                   "expected a sequence node, but found %s" % node.id,
+                                   node.start_mark)
         return [self.construct_object(child, deep=deep)
                 for child in node.value]
 
     def construct_mapping(self, node, deep=False):
         if not isinstance(node, MappingNode):
             raise ConstructorError(None, None,
-                    "expected a mapping node, but found %s" % node.id,
-                    node.start_mark)
+                                   "expected a mapping node, but found %s" % node.id,
+                                   node.start_mark)
         mapping = {}
         for key_node, value_node in node.value:
             key = self.construct_object(key_node, deep=deep)
@@ -134,7 +137,7 @@ class BaseConstructor(object):
                 hash(key)
             except TypeError, exc:
                 raise ConstructorError("while constructing a mapping", node.start_mark,
-                        "found unacceptable key (%s)" % exc, key_node.start_mark)
+                                       "found unacceptable key (%s)" % exc, key_node.start_mark)
             value = self.construct_object(value_node, deep=deep)
             mapping[key] = value
         return mapping
@@ -142,8 +145,8 @@ class BaseConstructor(object):
     def construct_pairs(self, node, deep=False):
         if not isinstance(node, MappingNode):
             raise ConstructorError(None, None,
-                    "expected a mapping node, but found %s" % node.id,
-                    node.start_mark)
+                                   "expected a mapping node, but found %s" % node.id,
+                                   node.start_mark)
         pairs = []
         for key_node, value_node in node.value:
             key = self.construct_object(key_node, deep=deep)
@@ -155,16 +158,18 @@ class BaseConstructor(object):
         if not 'yaml_constructors' in cls.__dict__:
             cls.yaml_constructors = cls.yaml_constructors.copy()
         cls.yaml_constructors[tag] = constructor
+
     add_constructor = classmethod(add_constructor)
 
     def add_multi_constructor(cls, tag_prefix, multi_constructor):
         if not 'yaml_multi_constructors' in cls.__dict__:
             cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
         cls.yaml_multi_constructors[tag_prefix] = multi_constructor
+
     add_multi_constructor = classmethod(add_multi_constructor)
 
-class SafeConstructor(BaseConstructor):
 
+class SafeConstructor(BaseConstructor):
     def construct_scalar(self, node):
         if isinstance(node, MappingNode):
             for key_node, value_node in node.value:
@@ -187,9 +192,9 @@ class SafeConstructor(BaseConstructor):
                     for subnode in value_node.value:
                         if not isinstance(subnode, MappingNode):
                             raise ConstructorError("while constructing a mapping",
-                                    node.start_mark,
-                                    "expected a mapping for merging, but found %s"
-                                    % subnode.id, subnode.start_mark)
+                                                   node.start_mark,
+                                                   "expected a mapping for merging, but found %s"
+                                                   % subnode.id, subnode.start_mark)
                         self.flatten_mapping(subnode)
                         submerge.append(subnode.value)
                     submerge.reverse()
@@ -197,8 +202,8 @@ class SafeConstructor(BaseConstructor):
                         merge.extend(value)
                 else:
                     raise ConstructorError("while constructing a mapping", node.start_mark,
-                            "expected a mapping or list of mappings for merging, but found %s"
-                            % value_node.id, value_node.start_mark)
+                                           "expected a mapping or list of mappings for merging, but found %s"
+                                           % value_node.id, value_node.start_mark)
             elif key_node.tag == u'tag:yaml.org,2002:value':
                 key_node.tag = u'tag:yaml.org,2002:str'
                 index += 1
@@ -217,12 +222,12 @@ class SafeConstructor(BaseConstructor):
         return None
 
     bool_values = {
-        u'yes':     True,
-        u'no':      False,
-        u'true':    True,
-        u'false':   False,
-        u'on':      True,
-        u'off':     False,
+        u'yes': True,
+        u'no': False,
+        u'true': True,
+        u'false': False,
+        u'on': True,
+        u'off': False,
     }
 
     def construct_yaml_bool(self, node):
@@ -240,27 +245,27 @@ class SafeConstructor(BaseConstructor):
         if value == '0':
             return 0
         elif value.startswith('0b'):
-            return sign*int(value[2:], 2)
+            return sign * int(value[2:], 2)
         elif value.startswith('0x'):
-            return sign*int(value[2:], 16)
+            return sign * int(value[2:], 16)
         elif value[0] == '0':
-            return sign*int(value, 8)
+            return sign * int(value, 8)
         elif ':' in value:
             digits = [int(part) for part in value.split(':')]
             digits.reverse()
             base = 1
             value = 0
             for digit in digits:
-                value += digit*base
+                value += digit * base
                 base *= 60
-            return sign*value
+            return sign * value
         else:
-            return sign*int(value)
+            return sign * int(value)
 
     inf_value = 1e300
-    while inf_value != inf_value*inf_value:
+    while inf_value != inf_value * inf_value:
         inf_value *= inf_value
-    nan_value = -inf_value/inf_value   # Trying to make a quiet NaN (like C99).
+    nan_value = -inf_value / inf_value  # Trying to make a quiet NaN (like C99).
 
     def construct_yaml_float(self, node):
         value = str(self.construct_scalar(node))
@@ -271,7 +276,7 @@ class SafeConstructor(BaseConstructor):
         if value[0] in '+-':
             value = value[1:]
         if value == '.inf':
-            return sign*self.inf_value
+            return sign * self.inf_value
         elif value == '.nan':
             return self.nan_value
         elif ':' in value:
@@ -280,11 +285,11 @@ class SafeConstructor(BaseConstructor):
             base = 1
             value = 0.0
             for digit in digits:
-                value += digit*base
+                value += digit * base
                 base *= 60
-            return sign*value
+            return sign * value
         else:
-            return sign*float(value)
+            return sign * float(value)
 
     def construct_yaml_binary(self, node):
         value = self.construct_scalar(node)
@@ -292,10 +297,10 @@ class SafeConstructor(BaseConstructor):
             return str(value).decode('base64')
         except (binascii.Error, UnicodeEncodeError), exc:
             raise ConstructorError(None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark) 
+                                   "failed to decode base64 data: %s" % exc, node.start_mark)
 
     timestamp_regexp = re.compile(
-            ur'''^(?P<year>[0-9][0-9][0-9][0-9])
+        ur'''^(?P<year>[0-9][0-9][0-9][0-9])
                 -(?P<month>[0-9][0-9]?)
                 -(?P<day>[0-9][0-9]?)
                 (?:(?:[Tt]|[ \t]+)
@@ -343,16 +348,16 @@ class SafeConstructor(BaseConstructor):
         yield omap
         if not isinstance(node, SequenceNode):
             raise ConstructorError("while constructing an ordered map", node.start_mark,
-                    "expected a sequence, but found %s" % node.id, node.start_mark)
+                                   "expected a sequence, but found %s" % node.id, node.start_mark)
         for subnode in node.value:
             if not isinstance(subnode, MappingNode):
                 raise ConstructorError("while constructing an ordered map", node.start_mark,
-                        "expected a mapping of length 1, but found %s" % subnode.id,
-                        subnode.start_mark)
+                                       "expected a mapping of length 1, but found %s" % subnode.id,
+                                       subnode.start_mark)
             if len(subnode.value) != 1:
                 raise ConstructorError("while constructing an ordered map", node.start_mark,
-                        "expected a single mapping item, but found %d items" % len(subnode.value),
-                        subnode.start_mark)
+                                       "expected a single mapping item, but found %d items" % len(subnode.value),
+                                       subnode.start_mark)
             key_node, value_node = subnode.value[0]
             key = self.construct_object(key_node)
             value = self.construct_object(value_node)
@@ -364,16 +369,16 @@ class SafeConstructor(BaseConstructor):
         yield pairs
         if not isinstance(node, SequenceNode):
             raise ConstructorError("while constructing pairs", node.start_mark,
-                    "expected a sequence, but found %s" % node.id, node.start_mark)
+                                   "expected a sequence, but found %s" % node.id, node.start_mark)
         for subnode in node.value:
             if not isinstance(subnode, MappingNode):
                 raise ConstructorError("while constructing pairs", node.start_mark,
-                        "expected a mapping of length 1, but found %s" % subnode.id,
-                        subnode.start_mark)
+                                       "expected a mapping of length 1, but found %s" % subnode.id,
+                                       subnode.start_mark)
             if len(subnode.value) != 1:
                 raise ConstructorError("while constructing pairs", node.start_mark,
-                        "expected a single mapping item, but found %d items" % len(subnode.value),
-                        subnode.start_mark)
+                                       "expected a single mapping item, but found %d items" % len(subnode.value),
+                                       subnode.start_mark)
             key_node, value_node = subnode.value[0]
             key = self.construct_object(key_node)
             value = self.construct_object(value_node)
@@ -415,62 +420,63 @@ class SafeConstructor(BaseConstructor):
 
     def construct_undefined(self, node):
         raise ConstructorError(None, None,
-                "could not determine a constructor for the tag %r" % node.tag.encode('utf-8'),
-                node.start_mark)
+                               "could not determine a constructor for the tag %r" % node.tag.encode('utf-8'),
+                               node.start_mark)
+
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:null',
-        SafeConstructor.construct_yaml_null)
+    u'tag:yaml.org,2002:null',
+    SafeConstructor.construct_yaml_null)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:bool',
-        SafeConstructor.construct_yaml_bool)
+    u'tag:yaml.org,2002:bool',
+    SafeConstructor.construct_yaml_bool)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:int',
-        SafeConstructor.construct_yaml_int)
+    u'tag:yaml.org,2002:int',
+    SafeConstructor.construct_yaml_int)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:float',
-        SafeConstructor.construct_yaml_float)
+    u'tag:yaml.org,2002:float',
+    SafeConstructor.construct_yaml_float)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:binary',
-        SafeConstructor.construct_yaml_binary)
+    u'tag:yaml.org,2002:binary',
+    SafeConstructor.construct_yaml_binary)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:timestamp',
-        SafeConstructor.construct_yaml_timestamp)
+    u'tag:yaml.org,2002:timestamp',
+    SafeConstructor.construct_yaml_timestamp)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:omap',
-        SafeConstructor.construct_yaml_omap)
+    u'tag:yaml.org,2002:omap',
+    SafeConstructor.construct_yaml_omap)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:pairs',
-        SafeConstructor.construct_yaml_pairs)
+    u'tag:yaml.org,2002:pairs',
+    SafeConstructor.construct_yaml_pairs)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:set',
-        SafeConstructor.construct_yaml_set)
+    u'tag:yaml.org,2002:set',
+    SafeConstructor.construct_yaml_set)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:str',
-        SafeConstructor.construct_yaml_str)
+    u'tag:yaml.org,2002:str',
+    SafeConstructor.construct_yaml_str)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:seq',
-        SafeConstructor.construct_yaml_seq)
+    u'tag:yaml.org,2002:seq',
+    SafeConstructor.construct_yaml_seq)
 
 SafeConstructor.add_constructor(
-        u'tag:yaml.org,2002:map',
-        SafeConstructor.construct_yaml_map)
+    u'tag:yaml.org,2002:map',
+    SafeConstructor.construct_yaml_map)
 
 SafeConstructor.add_constructor(None,
-        SafeConstructor.construct_undefined)
+                                SafeConstructor.construct_undefined)
 
-class Constructor(SafeConstructor):
 
+class Constructor(SafeConstructor):
     def construct_python_str(self, node):
         return self.construct_scalar(node).encode('utf-8')
 
@@ -481,7 +487,7 @@ class Constructor(SafeConstructor):
         return long(self.construct_yaml_int(node))
 
     def construct_python_complex(self, node):
-       return complex(self.construct_scalar(node))
+        return complex(self.construct_scalar(node))
 
     def construct_python_tuple(self, node):
         return tuple(self.construct_sequence(node))
@@ -489,21 +495,21 @@ class Constructor(SafeConstructor):
     def find_python_module(self, name, mark):
         if not name:
             raise ConstructorError("while constructing a Python module", mark,
-                    "expected non-empty name appended to the tag", mark)
+                                   "expected non-empty name appended to the tag", mark)
         try:
             __import__(name)
         except ImportError, exc:
             raise ConstructorError("while constructing a Python module", mark,
-                    "cannot find module %r (%s)" % (name.encode('utf-8'), exc), mark)
+                                   "cannot find module %r (%s)" % (name.encode('utf-8'), exc), mark)
         return sys.modules[name]
 
     def find_python_name(self, name, mark):
         if not name:
             raise ConstructorError("while constructing a Python object", mark,
-                    "expected non-empty name appended to the tag", mark)
+                                   "expected non-empty name appended to the tag", mark)
         if u'.' in name:
             # Python 2.4 only
-            #module_name, object_name = name.rsplit('.', 1)
+            # module_name, object_name = name.rsplit('.', 1)
             items = name.split('.')
             object_name = items.pop()
             module_name = '.'.join(items)
@@ -514,40 +520,41 @@ class Constructor(SafeConstructor):
             __import__(module_name)
         except ImportError, exc:
             raise ConstructorError("while constructing a Python object", mark,
-                    "cannot find module %r (%s)" % (module_name.encode('utf-8'), exc), mark)
+                                   "cannot find module %r (%s)" % (module_name.encode('utf-8'), exc), mark)
         module = sys.modules[module_name]
         if not hasattr(module, object_name):
             raise ConstructorError("while constructing a Python object", mark,
-                    "cannot find %r in the module %r" % (object_name.encode('utf-8'),
-                        module.__name__), mark)
+                                   "cannot find %r in the module %r" % (object_name.encode('utf-8'),
+                                                                        module.__name__), mark)
         return getattr(module, object_name)
 
     def construct_python_name(self, suffix, node):
         value = self.construct_scalar(node)
         if value:
             raise ConstructorError("while constructing a Python name", node.start_mark,
-                    "expected the empty value, but found %r" % value.encode('utf-8'),
-                    node.start_mark)
+                                   "expected the empty value, but found %r" % value.encode('utf-8'),
+                                   node.start_mark)
         return self.find_python_name(suffix, node.start_mark)
 
     def construct_python_module(self, suffix, node):
         value = self.construct_scalar(node)
         if value:
             raise ConstructorError("while constructing a Python module", node.start_mark,
-                    "expected the empty value, but found %r" % value.encode('utf-8'),
-                    node.start_mark)
+                                   "expected the empty value, but found %r" % value.encode('utf-8'),
+                                   node.start_mark)
         return self.find_python_module(suffix, node.start_mark)
 
-    class classobj: pass
+    class classobj:
+        pass
 
     def make_python_instance(self, suffix, node,
-            args=None, kwds=None, newobj=False):
+                             args=None, kwds=None, newobj=False):
         if not args:
             args = []
         if not kwds:
             kwds = {}
         cls = self.find_python_name(suffix, node.start_mark)
-        if newobj and isinstance(cls, type(self.classobj))  \
+        if newobj and isinstance(cls, type(self.classobj)) \
                 and not args and not kwds:
             instance = self.classobj()
             instance.__class__ = cls
@@ -618,6 +625,7 @@ class Constructor(SafeConstructor):
     def construct_python_object_new(self, suffix, node):
         return self.construct_python_object_apply(suffix, node, newobj=True)
 
+
 Constructor.add_constructor(
     u'tag:yaml.org,2002:python/none',
     Constructor.construct_yaml_null)
@@ -681,4 +689,3 @@ Constructor.add_multi_constructor(
 Constructor.add_multi_constructor(
     u'tag:yaml.org,2002:python/object/new:',
     Constructor.construct_python_object_new)
-
diff --git a/tablib/packages/yaml3/composer.py b/tablib/packages/yaml3/composer.py
index d5c6a7a..97c1306 100644
--- a/tablib/packages/yaml3/composer.py
+++ b/tablib/packages/yaml3/composer.py
@@ -1,15 +1,17 @@
-
 __all__ = ['Composer', 'ComposerError']
 
 from .error import MarkedYAMLError
-from .events import *
-from .nodes import *
+from error import MarkedYAMLError
+from events import StreamEndEvent, StreamStartEvent, AliasEvent, SequenceEndEvent, SequenceStartEvent, MappingEndEvent,\
+    MappingStartEvent, ScalarEvent
+from nodes import MappingNode, ScalarNode, SequenceNode
+
 
 class ComposerError(MarkedYAMLError):
     pass
 
-class Composer:
 
+class Composer:
     def __init__(self):
         self.anchors = {}
 
@@ -39,8 +41,8 @@ class Composer:
         if not self.check_event(StreamEndEvent):
             event = self.get_event()
             raise ComposerError("expected a single document in the stream",
-                    document.start_mark, "but found another document",
-                    event.start_mark)
+                                document.start_mark, "but found another document",
+                                event.start_mark)
 
         # Drop the STREAM-END event.
         self.get_event()
@@ -66,15 +68,14 @@ class Composer:
             anchor = event.anchor
             if anchor not in self.anchors:
                 raise ComposerError(None, None, "found undefined alias %r"
-                        % anchor, event.start_mark)
+                                    % anchor, event.start_mark)
             return self.anchors[anchor]
         event = self.peek_event()
         anchor = event.anchor
-        if anchor is not None:
-            if anchor in self.anchors:
+        if anchor is not None and anchor in self.anchors:
                 raise ComposerError("found duplicate anchor %r; first occurence"
-                        % anchor, self.anchors[anchor].start_mark,
-                        "second occurence", event.start_mark)
+                                    % anchor, self.anchors[anchor].start_mark,
+                                    "second occurence", event.start_mark)
         self.descend_resolver(parent, index)
         if self.check_event(ScalarEvent):
             node = self.compose_scalar_node(anchor)
@@ -91,7 +92,7 @@ class Composer:
         if tag is None or tag == '!':
             tag = self.resolve(ScalarNode, event.value, event.implicit)
         node = ScalarNode(tag, event.value,
-                event.start_mark, event.end_mark, style=event.style)
+                          event.start_mark, event.end_mark, style=event.style)
         if anchor is not None:
             self.anchors[anchor] = node
         return node
@@ -102,8 +103,8 @@ class Composer:
         if tag is None or tag == '!':
             tag = self.resolve(SequenceNode, None, start_event.implicit)
         node = SequenceNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
+                            start_event.start_mark, None,
+                            flow_style=start_event.flow_style)
         if anchor is not None:
             self.anchors[anchor] = node
         index = 0
@@ -120,20 +121,19 @@ class Composer:
         if tag is None or tag == '!':
             tag = self.resolve(MappingNode, None, start_event.implicit)
         node = MappingNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
+                           start_event.start_mark, None,
+                           flow_style=start_event.flow_style)
         if anchor is not None:
             self.anchors[anchor] = node
         while not self.check_event(MappingEndEvent):
-            #key_event = self.peek_event()
+            # key_event = self.peek_event()
             item_key = self.compose_node(node, None)
-            #if item_key in node.value:
+            # if item_key in node.value:
             #    raise ComposerError("while composing a mapping", start_event.start_mark,
             #            "found duplicate key", key_event.start_mark)
             item_value = self.compose_node(node, item_key)
-            #node.value[item_key] = item_value
+            # node.value[item_key] = item_value
             node.value.append((item_key, item_value))
         end_event = self.get_event()
         node.end_mark = end_event.end_mark
         return node
-
diff --git a/tablib/packages/yaml3/constructor.py b/tablib/packages/yaml3/constructor.py
index bd25b79..3fc9c7f 100644
--- a/tablib/packages/yaml3/constructor.py
+++ b/tablib/packages/yaml3/constructor.py
@@ -5,7 +5,13 @@ __all__ = ['BaseConstructor', 'SafeConstructor', 'Constructor',
 from .error import *
 from .nodes import *
 
-import collections, datetime, base64, binascii, re, sys, types
+import base64
+import binascii
+import collections
+import datetime
+import re
+import sys
+import types
 
 class ConstructorError(MarkedYAMLError):
     pass