[{'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:# drop cols from station 1 that won't be used in model\ndrop_cols = ['Heat', 'Cool', 'Depart', 'NightLength_MPrec', 'NightLength_NearH',\n            'blended_Depart', 'blended_Heat', 'blended_Cool']\n\ntrain_station_1 = train_station_1.drop(drop_cols, axis= 1)\ntest_station_1 = test_station_1.drop(drop_cols, axis= 1)   "}, {'role': 'assistant', 'content': 'data_preprocessing'}]