[{'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:language_distance = {'language' : ['en', 'du', 'fr', 'es'],\n                     'levenshtein_distance_from_en' : [0, 72.61, 92.06, 92.25]}\n\nlanguage_distance = pd.DataFrame(language_distance)\n\ntrain_users = pd.merge(train_users, language_distance, on = 'language', how = 'left')\ntest_users = pd.merge(test_users, language_distance, on = 'language', how = 'left')\n\n"}, {'role': 'assistant', 'content': 'data_preprocessing'}]