[{'role': 'system', 'content': "You are an expert in machine learning and your task is to classify the code snippets into categories from the provided list of categories. List of categories: ['helper_functions', 'load_data', 'data_exploration', 'data_preprocessing', 'evaluation', 'modelling', 'prediction', 'result_visualization', 'save_results', 'comment_only']"}, {'role': 'user', 'content': "Identify to which category the provided code belongs and assign the code snippet to at least 1 but up to 5 categories based on the probabilities, ignore if the probability of the category is negligible. Strictly provide your response as a list. Avoid providing any additional information, commentary, or personal opinions.\\nPython Code:for data in (train, test):\n    data['year_created']  = data['date_account_created'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[:4]) )\n    data['month_created'] = data['date_account_created'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[5:7]))\n    data['week_created']  = data['date_account_created'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[8:10]))\n    \n    data['year_first']  = data['date_first_booking'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[:4]))\n    data['month_first'] = data['date_first_booking'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[5:7]))\n    data['week_first']  = data['date_first_booking'].apply(lambda x: 'nan' if str(x) == 'nan' else int(str(x)[8:10]))\n"}, {'role': 'assistant', 'content': "['data_preprocessing']"}]