def from_dict(self, dic):
        """Import data from a {cluster: {field: value}} dictionary."""
        self._reset_data()
        for cluster, vals in dic.items():
            for field, value in vals.items():
                self.set(field, [cluster], value, add_to_stack=False)
        self._data_base = deepcopy(self._data)
Import data from a {cluster: {field: value}} dictionary.