[{'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:def create_extra_features(train_ext):\n    train_ext['null_sum'] = train_ext[train_ext==-1].count(axis=1)\n    #train_ext['bin_sum']  = train_ext[col_binary].sum(axis=1)\n    train_ext['ord_sum']  = train_ext[col_ordinal].sum(axis=1)\n    train_ext['interval_median']  = train_ext[col_interval].sum(axis=1)\n    train_ext['new_amount_borrowed_by_income']  = train_ext['amount_borrowed']/train_ext['income']\n    train_ext['new_amount_borrowed_by_months']  = train_ext['amount_borrowed']/train_ext['borrowed_in_months']\n    return train_ext"}, {'role': 'assistant', 'content': "['data_preprocessing']"}]