Return the cftime date type for a given calendar name.

def get_date_type(calendar):
    """Return the cftime date type for a given calendar name."""
    try:
        import cftime
    except ImportError:
        raise ImportError(
            'cftime is required for dates with non-standard calendars')
    else:
        calendars = {
            'noleap': cftime.DatetimeNoLeap,
            '360_day': cftime.Datetime360Day,
            '365_day': cftime.DatetimeNoLeap,
            '366_day': cftime.DatetimeAllLeap,
            'gregorian': cftime.DatetimeGregorian,
            'proleptic_gregorian': cftime.DatetimeProlepticGregorian,
            'julian': cftime.DatetimeJulian,
            'all_leap': cftime.DatetimeAllLeap,
            'standard': cftime.DatetimeGregorian
        }
        return calendars[calendar]