docs: def excel_datetime(timestamp, epoch=None):
      """Return datetime object from timestamp in Excel serial format.
  
      Convert LSM time stamps.
  
      >>> excel_datetime(40237.029999999795)
      datetime.datetime(2010, 2, 28, 0, 43, 11, 999982)
  
      """
      if epoch is None:
          epoch = datetime.datetime.fromordinal(693594)
      return epoch + datetime.timedelta(timestamp)