[{'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:test_fixed_cols = ['ForecastId', 'Province_State', 'Country_Region', 'Date']\nfixed_cols = ['Id', 'province', 'country', 'date']\noutput_cols = ['cc_cases', 'ft_cases']\ninput_cols = list(set(train_df.columns.to_list()) - set(fixed_cols) - set(output_cols))\nprint('output columns are ', output_cols)\nprint('input columns are ', input_cols)\nX = train_df[input_cols]\ny = train_df[output_cols]"}, {'role': 'assistant', 'content': 'data_preprocessing'}]