'Returns a time-zone representing UTC.
Same as TimeZoneInfo(\'GMT Standard Time\', True) but caches the result
for performance.
>>> isinstance(TimeZoneInfo.utc(), TimeZoneInfo)
True'

@classmethod
def utc(class_):

    if (not ('_tzutc' in class_.__dict__)):
        setattr(class_, '_tzutc', class_('GMT    Standard    Time', True))
    return class_._tzutc
