[{'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:# fill NaN values\nhomesite_df.fillna(homesite_df.mean(), inplace=True)\ntest_df.fillna(test_df.mean(), inplace=True)\n     \n# define training and testing sets\nX_train = homesite_df.drop("QuoteConversion_Flag",axis=1)\nY_train = homesite_df["QuoteConversion_Flag"]\nX_test  = test_df.drop("QuoteNumber",axis=1).copy()\n\nX_train = maxabs_scale(X_train)\nX_test = maxabs_scale(X_test)'}, {'role': 'assistant', 'content': 'data_preprocessing'}]