docs: def pop(self, symbol):
          """
          Delete current metadata of `symbol`
  
          Parameters
          ----------
          symbol : `str`
              symbol name to delete
  
          Returns
          -------
          Deleted metadata
          """
          last_metadata = self.find_one({'symbol': symbol}, sort=[('start_time', pymongo.DESCENDING)])
          if last_metadata is None:
              raise NoDataFoundException('No metadata found for symbol {}'.format(symbol))
  
          self.find_one_and_delete({'symbol': symbol}, sort=[('start_time', pymongo.DESCENDING)])
          mongo_retry(self.find_one_and_update)({'symbol': symbol}, {'$unset': {'end_time': ''}},
                                                sort=[('start_time', pymongo.DESCENDING)])
  
          return last_metadata