'Retrieves an instance of an TradingCalendar whose name is given.
Parameters
name : str
The name of the TradingCalendar to be retrieved.
Returns
calendar : zipline.utils.calendars.TradingCalendar
The desired calendar.'

def get_calendar(self, name):

    canonical_name = self.resolve_alias(name)
    try:
        return self._calendars[canonical_name]
    except KeyError:
        pass
    try:
        factory = self._calendar_factories[canonical_name]
    except KeyError:
        raise InvalidCalendarName(calendar_name=name)
    calendar = self._calendars[canonical_name] = factory()
    return calendar
