def _normalize_cell_name(self):

        if not self.obj_attr_is_set('cell_name') or self.cell_name is None:
            return
        cn_changed = 'cell_name' in self.obj_what_changed()
        if self.cell_name.startswith(cells_utils.BLOCK_SYNC_FLAG):
            self.cell_name = self.cell_name.replace(
                    cells_utils.BLOCK_SYNC_FLAG, '', 1)
            # cell_name is not normally an empty string, this means it was None
            # or unset before cells_utils.BLOCK_SYNC_FLAG was applied.
            if len(self.cell_name) == 0:
                self.cell_name = None
        if not cn_changed:
            self.obj_reset_changes(['cell_name'])
Returns the default value if the requested data doesn't exist
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/objects/instance.py/Instance._normalize_cell_name--crossover with--dataset/ETHPy150Open kdart/pycopia/aid/pycopia/dictlib.py/MultiValueDict.get