Return a description of the table and the ObjectAtoms to be created.

        :Returns:
        table_description : dict
          A Description of the pyTables table.
        ObjectAtomsn : dict
          A
      in terms of PyTables
        columns, and a

def _model_trace_description(self):
        """Return a description of the table and the ObjectAtoms to be created.

        :Returns:
        table_description : dict
          A Description of the pyTables table.
        ObjectAtomsn : dict
          A
      in terms of PyTables
        columns, and a"""
        D = {}
        for name, fun in six.iteritems(self.model._funs_to_tally):
            arr = asarray(fun())
            D[name] = tables.Col.from_dtype(dtype((arr.dtype, arr.shape)))
        return D, {}