<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def copy_data_item(self, data_item: DataItem) -> DataItem: """Copy a data item. .. versionadded:: 1.0 Scriptable: No """

        data_item = copy.deepcopy(data_item._data_item)
        self.__document_model.append_data_item(data_item)
        return DataItem(data_item)