[{'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:#Converting below columns as categories for plotting in graphs\ncategorical_features = [\n    'affiliate_channel',\n    'affiliate_provider',\n    'first_affiliate_tracked',\n    'first_browser',\n    'first_device_type',\n    'gender',\n    'language',\n    'signup_app',\n    'signup_method',\n    'signup_flow'\n]\n\nfor categorical_feature in categorical_features:\n    train[categorical_feature] = train[categorical_feature].astype('category')\nfor categorical_feature in categorical_features:\n    test[categorical_feature] = test[categorical_feature].astype('category')    "}, {'role': 'assistant', 'content': 'data_preprocessing'}]