code: def list_changes(self):
          
          if not self.is_attached():
              raise ItsdbError('changes are not tracked for detached tables.')
          return [(i, self[i]) for i, row in enumerate(self._records)
                  if row is not None]
docs: Return a list of modified records.
  
          This is only applicable for attached tables.
  
          Returns:
              A list of `(row_index, record)` tuples of modified records
          Raises:
              :class:`delphin.exceptions.ItsdbError`: when called on a
                  detached table