[{'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:common_value = "UNKNOWN"\n\n# Replacing all the Province_State that are null by the Country_Region values\ntrain_df.Province_State.fillna(train_df.Country_Region, inplace=True)\ntest_df.Province_State.fillna(test_df.Country_Region, inplace=True)\n\n# Handling the Date column\n# 1. Converting the object type column into datetime type\ntrain_df.Date = train_df.Date.apply(pd.to_datetime)\ntest_df.Date = test_df.Date.apply(pd.to_datetime)\n\n# 2. Creating new features\n#train_df[\'ReportDay_year\'] = train_df[\'Date\'].dt.year #Not required this column because all the data is of this year\ntrain_df[\'ReportDay_month\'] = train_df[\'Date\'].dt.month\ntrain_df[\'ReportDay_week\'] = train_df[\'Date\'].dt.week\ntrain_df[\'ReportDay_day\'] = train_df[\'Date\'].dt.day \n\n#test_df[\'ReportDay_year\'] = test_df[\'Date\'].dt.year\ntest_df[\'ReportDay_month\'] = test_df[\'Date\'].dt.month\ntest_df[\'ReportDay_week\'] = test_df[\'Date\'].dt.week\ntest_df[\'ReportDay_day\'] = test_df[\'Date\'].dt.day\''}, {'role': 'assistant', 'content': 'data_preprocessing'}]