[{'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:def countVowels(string):\nnum_vowels=0\nfor char in string:\nif char in "aeiou":\nnum_vowels = num_vowels+1\nreturn num_vowels\ncombined[\'NoOfVowels\'] = combined.name.map(lambda name: countVowels(name))\ndef countEI(string):\nnum_ei=0\nfor char in string:\nif char in "ei":\nnum_ei = num_ei+1\nreturn num_ei\ncombined[\'NumEI\'] = combined.name.map(lambda name: countEI(name))'}, {'role': 'assistant', 'content': 'data_preprocessing'}]