[{'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:# Impute missing value in categorical columns with mode\nnot_numeric_cols = df.select_dtypes(exclude=['number']).columns.values\n\nfor col in not_numeric_cols:\n    if col in list(col_pct_miss_df.column_name):\n        mode = df[col].mode()[0]\n        df[col] = df[col].fillna(mode)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]