[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify code snippets into one of the following categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']."}, {'role': 'user', 'content': "Identify the single most appropriate category to which the provided code belongs. Provide your response as a single category label without any additional information, commentary, or personal opinions.\\nPython Code:# X_train['Date2'] = pd.to_datetime(X_train['Date'], utc = True)\n# X_test['Date2'] = pd.to_datetime(X_test['Date'], utc = True)\n\n# X_train['Weekly_Sales_Lag_52_Weeks'] = X_train.merge(X_all, \n#                                                    left_on=['Store', 'Dept', 'Date2'], \n#                                                    right_on=['Store', 'Dept', 'Date2'],\n#                                                    how='inner')['Weekly_Sales_Lag_52_Weeks']\n# X_test['Weekly_Sales_Lag_52_Weeks'] = X_test.merge(X_all, \n#                                                  left_on=['Store', 'Dept', 'Date2'], \n#                                                  right_on=['Store', 'Dept', 'Date2'],\n#                                                  how='inner')['Weekly_Sales_Lag_52_Weeks']\n\n# X_test.head()"}, {'role': 'assistant', 'content': 'helper_functions'}]