Remove unused imports (#147)

Discovered using the command:

    flake8 --select F401 .

9 files changed, 9 insertions, 12 deletions

diff --git a/examples/SimpleCalc.py b/examples/SimpleCalc.py
index d52a20f..5e1d835 100644
--- a/examples/SimpleCalc.py
+++ b/examples/SimpleCalc.py
@@ -33,7 +33,7 @@ debug_flag=False
 
 variables = {}
 
-from fourFn import BNF, exprStack, fn, opn, evaluate_stack
+from fourFn import BNF, exprStack, evaluate_stack
 
 # from fourFn import BNF, exprStack, fn, opn
 # def evaluateStack( s ):
diff --git a/examples/fourFn.py b/examples/fourFn.py
index e07125f..e5be215 100644
--- a/examples/fourFn.py
+++ b/examples/fourFn.py
@@ -11,7 +11,7 @@
 # Copyright 2003-2019 by Paul McGuire
 #
 from pyparsing import (Literal, Word, Group, Forward, alphas, alphanums, Regex, ParseException,
-                       CaselessKeyword, Suppress, delimitedList, pyparsing_common as ppc, tokenMap)
+                       CaselessKeyword, Suppress, delimitedList)
 import math
 import operator
 
diff --git a/examples/htmlStripper.py b/examples/htmlStripper.py
index eb35c70..bd99b77 100644
--- a/examples/htmlStripper.py
+++ b/examples/htmlStripper.py
@@ -6,10 +6,9 @@
 #
 # Copyright (c) 2006, 2016, Paul McGuire
 #
-import urllib.parse, urllib.error
 from urllib.request import urlopen
 from pyparsing import (makeHTMLTags, commonHTMLEntity, replaceHTMLEntity,
-    htmlComment, anyOpenTag, anyCloseTag, LineEnd, OneOrMore, replaceWith)
+    htmlComment, anyOpenTag, anyCloseTag, LineEnd, replaceWith)
 
 scriptOpen, scriptClose = makeHTMLTags("script")
 scriptBody = scriptOpen + scriptOpen.tag_body + scriptClose
diff --git a/examples/protobuf_parser.py b/examples/protobuf_parser.py
index 52ce434..e1657b4 100644
--- a/examples/protobuf_parser.py
+++ b/examples/protobuf_parser.py
@@ -6,7 +6,7 @@
 #
 
 from pyparsing import (Word, alphas, alphanums, Regex, Suppress, Forward,
-    Keyword, Group, oneOf, ZeroOrMore, Optional, delimitedList,
+    Group, oneOf, ZeroOrMore, Optional, delimitedList,
     restOfLine, quotedString, Dict)
 
 ident = Word(alphas+"_",alphanums+"_").setName("identifier")
diff --git a/examples/sexpParser.py b/examples/sexpParser.py
index 0d006d2..f678d9a 100644
--- a/examples/sexpParser.py
+++ b/examples/sexpParser.py
@@ -45,7 +45,6 @@ BNF reference: http://theory.lcs.mit.edu/~rivest/sexp.txt
 
 import pyparsing as pp
 from base64 import b64decode
-import pprint
 
 
 def verify_length(s, l, t):
diff --git a/examples/simpleSQL.py b/examples/simpleSQL.py
index ac4de17..60582cd 100644
--- a/examples/simpleSQL.py
+++ b/examples/simpleSQL.py
@@ -8,11 +8,11 @@
 from pyparsing import Word, delimitedList, Optional, \
     Group, alphas, alphanums, Forward, oneOf, quotedString, \
     infixNotation, opAssoc, \
-    ZeroOrMore, restOfLine, CaselessKeyword, pyparsing_common as ppc
+    restOfLine, CaselessKeyword, pyparsing_common as ppc
 
 # define SQL tokens
 selectStmt = Forward()
-SELECT, FROM, WHERE, AND, OR, IN, IS, NOT, NULL = map(CaselessKeyword, 
+SELECT, FROM, WHERE, AND, OR, IN, IS, NOT, NULL = map(CaselessKeyword,
     "select from where and or in is not null".split())
 NOT_NULL = NOT + NULL
 
diff --git a/examples/urlExtractorNew.py b/examples/urlExtractorNew.py
index 795322a..14f6eb1 100644
--- a/examples/urlExtractorNew.py
+++ b/examples/urlExtractorNew.py
@@ -1,7 +1,6 @@
 # URL extractor
 # Copyright 2004, Paul McGuire
 from pyparsing import makeHTMLTags
-import urllib.parse, urllib.error
 from urllib.request import urlopen
 import pprint
 
diff --git a/pyparsing.py b/pyparsing.py
index f4f0735..1a7a4e0 100644
--- a/pyparsing.py
+++ b/pyparsing.py
@@ -112,7 +112,7 @@ import pprint
 import traceback
 import types
 from datetime import datetime
-from operator import itemgetter, attrgetter
+from operator import itemgetter
 import itertools
 from functools import wraps
 from itertools import filterfalse
diff --git a/unitTests.py b/unitTests.py
index 7f516b1..f0a7ceb 100644
--- a/unitTests.py
+++ b/unitTests.py
@@ -1081,7 +1081,7 @@ class ReStringRangeTest(ParseTestCase):
 class SkipToParserTests(ParseTestCase):
     def runTest(self):
 
-        from pyparsing import Literal, SkipTo, cStyleComment, ParseBaseException, And, Word, alphas, nums, Optional, NotAny
+        from pyparsing import Literal, SkipTo, cStyleComment, ParseBaseException, And, Word, alphas, nums
 
         thingToFind = Literal('working')
         testExpr = SkipTo(Literal(';'), include=True, ignore=cStyleComment) + thingToFind
@@ -1113,7 +1113,7 @@ class SkipToParserTests(ParseTestCase):
         result = expr.parseString(text)
         self.assertTrue(isinstance(result.prefix, str), "SkipTo created with wrong saveAsList attribute")
 
-        from pyparsing import Literal, And, Word, alphas, nums, Optional, NotAny
+        from pyparsing import Literal, And, Word, alphas, nums
         alpha_word = (~Literal("end") + Word(alphas, asKeyword=True)).setName("alpha")
         num_word = Word(nums, asKeyword=True).setName("int")