[{'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:max_df = 0.03 # ignore terms that have a document frequency strictly higher than x% of docs (or occurs in > n docs if integer value)\nmin_df = 0.0007 # ignore terms that have a document frequency strictly less than x% of documents (or occurs in < n documents if integer value)\ntf_vectorizer = CountVectorizer(max_df=max_df, min_df=min_df,stop_words='english')\ntf = tf_vectorizer.fit_transform(comments_text)"}, {'role': 'assistant', 'content': 'modelling'}]