def _sanitize_dimensions(self, item):
    field = self.data_source._determine_fields(item)[0]
    finfo = self.data_source.ds.field_info[field]
    dimensions = Unit(finfo.units, registry=self.data_source.ds.unit_registry).dimensions
    if (dimensions not in self.known_dimensions):
        self.known_dimensions[dimensions] = item
        ret_item = item
    else:
        ret_item = self.known_dimensions[dimensions]
    return ret_item
def _sanitize_dimensions(self, item):
    field = self.data_source._determine_fields(item)[0]
    finfo = self.data_source.ds.field_info[field]
    dimensions = Unit(finfo.units, registry=self.data_source.ds.unit_registry).dimensions
    if (dimensions not in self.known_dimensions):
        self.known_dimensions[dimensions] = item
        ret_item = item
    else:
        ret_item = self.known_dimensions[dimensions]
    return ret_item