[{'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:class ImputeCategorical(BaseEstimator, TransformerMixin):\ndef __init__(self, columns=None):\nself.columns = columns\nself.imputer = None\ndef fit(self, data, target=None):\nif self.columns is None:\nself.columns = data.columns\nself.imputer = Imputer(missing_values=0, strategy=\'most_frequent\')\nself.imputer.fit(data[self.columns])\nreturn self\ndef transform(self, data):\n"""\nUses the encoders to transform a data frame.\n"""\noutput = data.copy()\noutput[self.columns] = self.imputer.transform(output[self.columns])\nreturn output\nimputer = ImputeCategorical([\'workclass\', \'native-country\', \'occupation\'])\ndata = imputer.fit_transform(data)'}, {'role': 'assistant', 'content': "['data_preprocessing']"}]