[{'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:df_exp[df_exp.Year==\'1990\'].IWUrbanPct.plot(figsize=(7,7), kind="hist", bins=13, label="1990", xlim=(0, 100), ylim=(0, 150), grid=True)\ndf_exp[df_exp.Year==\'2000\'].IWUrbanPct.plot(kind="hist", bins=13, label="2000", grid=True)\ndf_exp[df_exp.Year==\'2015\'].IWUrbanPct.plot(kind="hist", bins=13, label="2015", grid=True)\npyplot.title("Urban Access to Drinking Water")\npyplot.xlabel("Access Pct")\npyplot.ylabel("Number of Countries")\npyplot.legend()'}, {'role': 'assistant', 'content': 'data_exploration'}]