def timezone(zone):
r""" Return a datetime.tzinfo implementation for the given timezone
>>> from datetime import datetime, timedelta
>>> utc = timezone('UTC')
>>> eastern = timezone('US/Eastern')
>>> eastern.zone
'US/Eastern'
>>> timezone(unicode('US/Eastern')) is eastern
True
>>> utc_dt = datetime(2002, 10, 27, 6, 0, 0, tzinfo=utc)
>>> loc_dt = utc_dt.astimezone(eastern)
>>> fmt = '%Y-%m-%d %H:%M:%S %Z (%z)'
>>> loc_dt.strftime(fmt)
'2002-10-27 01:00:00 EST (-0500)'
>>> (loc_dt - timedelta(minutes=10)).strftime(fmt)
'2002-10-27 00:50:00 EST (-0500)'
>>> eastern.normalize(loc_dt - timedelta(minutes=10)).strftime(fmt)
'2002-10-27 01:50:00 EDT (-0400)'
>>> (loc_dt + timedelta(minutes=10)).strftime(fmt)
'2002-10-27 01:10:00 EST (-0500)'
Raises UnknownTimeZoneError if passed an unknown zone.
>>> try:
... timezone('Asia/Shangri-La')
... except UnknownTimeZoneError:
... print('Unknown')
Unknown
>>> try:
... timezone(unicode('\N{TRADE MARK SIGN}'))
... except UnknownTimeZoneError:
... print('Unknown')
Unknown
"""
if zone is None:
raise UnknownTimeZoneError(None)
if zone.upper() == "UTC":
return utc
try:
zone = ascii(zone)
except UnicodeEncodeError:
# All valid timezones are ASCII
raise UnknownTimeZoneError(zone)
zone = _case_insensitive_zone_lookup(_unmunge_zone(zone))
if zone not in _tzinfo_cache:
if zone in all_timezones_set: # noqa
fp = open_resource(zone)
try:
_tzinfo_cache[zone] = build_tzinfo(zone, fp)
finally:
fp.close()
else:
raise UnknownTimeZoneError(zone)
return _tzinfo_cache[zone]
