docs: def sub_filter(self, subset, filter, inplace=True):
          """Apply a filter to subset of the data
  
          Examples
          --------
  
          ::
  
              .subquery(
                  'timestep == 2',
                  'R > 4',
              )
  
          """
          # build the full query
          full_query = ''.join(('not (', subset, ') or not (', filter, ')'))
          with LogDataChanges(self, filter_action='filter', filter_query=filter):
              result = self.data.query(full_query, inplace=inplace)
          return result