1 files changed, 33 insertions, 29 deletions

diff --git a/src/isodate/isotzinfo.py b/src/isodate/isotzinfo.py
index a805ebe..d096dd3 100644
--- a/src/isodate/isotzinfo.py
+++ b/src/isodate/isotzinfo.py
@@ -24,41 +24,42 @@
 # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 # CONTRACT, STRICT LIABILITY, OR TORT
 ##############################################################################
-'''
+"""
 This module provides an ISO 8601:2004 time zone info parser.
 
 It offers a function to parse the time zone offset as specified by ISO 8601.
-'''
+"""
 import re
 
 from isodate.isoerror import ISO8601Error
 from isodate.tzinfo import UTC, FixedOffset, ZERO
 
-TZ_REGEX = r"(?P<tzname>(Z|(?P<tzsign>[+-])"\
-           r"(?P<tzhour>[0-9]{2})(:?(?P<tzmin>[0-9]{2}))?)?)"
+TZ_REGEX = (
+    r"(?P<tzname>(Z|(?P<tzsign>[+-])" r"(?P<tzhour>[0-9]{2})(:?(?P<tzmin>[0-9]{2}))?)?)"
+)
 
 TZ_RE = re.compile(TZ_REGEX)
 
 
-def build_tzinfo(tzname, tzsign='+', tzhour=0, tzmin=0):
-    '''
+def build_tzinfo(tzname, tzsign="+", tzhour=0, tzmin=0):
+    """
     create a tzinfo instance according to given parameters.
 
     tzname:
       'Z'       ... return UTC
       '' | None ... return None
       other     ... return FixedOffset
-    '''
-    if tzname is None or tzname == '':
+    """
+    if tzname is None or tzname == "":
         return None
-    if tzname == 'Z':
+    if tzname == "Z":
         return UTC
-    tzsign = ((tzsign == '-') and -1) or 1
+    tzsign = ((tzsign == "-") and -1) or 1
     return FixedOffset(tzsign * tzhour, tzsign * tzmin, tzname)
 
 
 def parse_tzinfo(tzstring):
-    '''
+    """
     Parses ISO 8601 time zone designators to tzinfo objecs.
 
     A time zone designator can be in the following format:
@@ -67,18 +68,21 @@ def parse_tzinfo(tzstring):
       +-hhmm  basic hours and minutes
       +-hh:mm extended hours and minutes
       +-hh    hours
-    '''
+    """
     match = TZ_RE.match(tzstring)
     if match:
         groups = match.groupdict()
-        return build_tzinfo(groups['tzname'], groups['tzsign'],
-                            int(groups['tzhour'] or 0),
-                            int(groups['tzmin'] or 0))
-    raise ISO8601Error('%s not a valid time zone info' % tzstring)
+        return build_tzinfo(
+            groups["tzname"],
+            groups["tzsign"],
+            int(groups["tzhour"] or 0),
+            int(groups["tzmin"] or 0),
+        )
+    raise ISO8601Error("%s not a valid time zone info" % tzstring)
 
 
-def tz_isoformat(dt, format='%Z'):
-    '''
+def tz_isoformat(dt, format="%Z"):
+    """
     return time zone offset ISO 8601 formatted.
     The various ISO formats can be chosen with the format parameter.
 
@@ -89,24 +93,24 @@ def tz_isoformat(dt, format='%Z'):
         %h ... +-HH
         %z ... +-HHMM
         %Z ... +-HH:MM
-    '''
+    """
     tzinfo = dt.tzinfo
     if (tzinfo is None) or (tzinfo.utcoffset(dt) is None):
-        return ''
+        return ""
     if tzinfo.utcoffset(dt) == ZERO and tzinfo.dst(dt) == ZERO:
-        return 'Z'
+        return "Z"
     tdelta = tzinfo.utcoffset(dt)
     seconds = tdelta.days * 24 * 60 * 60 + tdelta.seconds
-    sign = ((seconds < 0) and '-') or '+'
+    sign = ((seconds < 0) and "-") or "+"
     seconds = abs(seconds)
     minutes, seconds = divmod(seconds, 60)
     hours, minutes = divmod(minutes, 60)
     if hours > 99:
-        raise OverflowError('can not handle differences > 99 hours')
-    if format == '%Z':
-        return '%s%02d:%02d' % (sign, hours, minutes)
-    elif format == '%z':
-        return '%s%02d%02d' % (sign, hours, minutes)
-    elif format == '%h':
-        return '%s%02d' % (sign, hours)
+        raise OverflowError("can not handle differences > 99 hours")
+    if format == "%Z":
+        return "%s%02d:%02d" % (sign, hours, minutes)
+    elif format == "%z":
+        return "%s%02d%02d" % (sign, hours, minutes)
+    elif format == "%h":
+        return "%s%02d" % (sign, hours)
     raise ValueError('unknown format string "%s"' % format)