code: def _MakeTimestamp(self, start=None, end=None):
      
      mysql_unsigned_bigint_max = 18446744073709551615
      ts_start = int(start or 0)
      if end is None:
        ts_end = mysql_unsigned_bigint_max
      else:
        ts_end = int(end)
      if ts_start == 0 and ts_end == mysql_unsigned_bigint_max:
        return None
      else:
        return (ts_start, ts_end)
docs: Create a timestamp using a start and end time.
  
      Args:
        start: Start timestamp.
        end: End timestamp.
  
      Returns:
        A tuple (start, end) of converted timestamps or None for all time.