[{'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:split_at = len(x) - len(x) // 10\n(x_train, x_val) = x[:split_at], x[split_at:]\n(y_train, y_val) = y[:split_at], y[split_at:]\nprint('Training Data:')\nprint(x_train.shape)\nprint(y_train.shape)\nprint('Validation Data:')\nprint(x_val.shape)\nprint(y_val.shape)"}, {'role': 'assistant', 'content': 'data_preprocessing'}]