[{'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 calculateDuration(x):\nif len(x) ==1:\narbitraryMax = ((dt.datetime(2013,1,1) - dt.datetime(1970,1,1)).total_seconds())\nreturn arbitraryMax - min(x)\nreturn max(x) - min(x)\ndurationDf["when"] = durationDf["when"].apply(pd.to_numeric)\ndurationDfFinal = pd.DataFrame(durationDf.groupby("id")["when"].apply(calculateDuration))\ndurationDfFinal.columns = [\'duration\']'}, {'role': 'assistant', 'content': "['data_preprocessing']"}]