[{'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:# One-hot-encoding features\nohe_feats = ['gender', 'signup_method', 'signup_flow', 'language', \n             'affiliate_channel', 'affiliate_provider', \n             'first_affiliate_tracked', 'signup_app', \n             'first_device_type', 'first_browser']\nfor f in ohe_feats:\n    df_all_dummy = pd.get_dummies(df_all[f], prefix=f)\n    df_all = df_all.drop([f], axis=1)\n    df_all = pd.concat((df_all, df_all_dummy), axis=1)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]