def _load_calendar(self, freq, future):
    'Load original calendar timestamp from file.\n\n        Parameters\n        ----------\n        freq : str\n            frequency of read calendar file\n\n        Returns\n        ----------\n        list\n            list of timestamps\n        '
    if future:
        fname = self._uri_cal.format((freq + '_future'))
        if (not os.path.exists(fname)):
            get_module_logger('data').warning(f'{freq}_future.txt not exists, return current calendar!')
            fname = self._uri_cal.format(freq)
    else:
        fname = self._uri_cal.format(freq)
    if (not os.path.exists(fname)):
        raise ValueError(('calendar not exists for freq ' + freq))
    with open(fname) as f:
        return [pd.Timestamp(x.strip()) for x in f]
Load original calendar timestamp from file.

Parameters
----------
freq : str
    frequency of read calendar file

Returns
----------
list
    list of timestamps
def _load_calendar(self, freq, future):
    'Load original calendar timestamp from file.\n\n        Parameters\n        ----------\n        freq : str\n            frequency of read calendar file\n\n        Returns\n        ----------\n        list\n            list of timestamps\n        '
    if future:
        fname = self._uri_cal.format((freq + '_future'))
        if (not os.path.exists(fname)):
            get_module_logger('data').warning(f'{freq}_future.txt not exists, return current calendar!')
            fname = self._uri_cal.format(freq)
    else:
        fname = self._uri_cal.format(freq)
    if (not os.path.exists(fname)):
        raise ValueError(('calendar not exists for freq ' + freq))
    with open(fname) as f:
        return [pd.Timestamp(x.strip()) for x in f]