[{'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:HIV2001 = HIV.ix[:,[0,4]]\nHIV2005 = HIV.ix[:,[0,3]]\nHIV2009 = HIV.ix[:,[0,2]]\nHIV2013 = HIV.ix[:,[0,1]]\nHIV2001["Year"] = pd.to_datetime(2001, format = \'%Y\')\nHIV2005["Year"] = pd.to_datetime(2005, format = \'%Y\')\nHIV2009["Year"] = pd.to_datetime(2009, format = \'%Y\')\nHIV2013["Year"] = pd.to_datetime(2013, format = \'%Y\')'}, {'role': 'assistant', 'content': "['data_preprocessing']"}]