[{'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:train.drop(['Tests','Test Pop', 'Density', 'Urban Pop', 'sex0', 'sex14',\n            'sex25', 'sex54', 'sex64', 'sex65plus', 'Sex Ratio', 'lung',\n            'Female Lung', 'Male Lung', 'Crime Index', 'Population 2020',\n            'Smoking 2016', 'Females 2018', 'Total Infected','Total Deaths',\n            'Total Recovered', 'Hospital Bed', 'Median Age', 'GDP 2018'], axis = 1, inplace = True)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]