code: def _strptime(expr, date_format):
      
  
      return _string_op(expr, Strptime, _date_format=date_format,
                        output_type=types.datetime)
docs: Return datetimes specified by date_format,
      which supports the same string format as the python standard library.
      Details of the string format can be found in python string format doc
  
      :param expr:
      :param date_format: date format string (e.g. “%Y-%m-%d”)
      :type date_format: str
      :return: