[{'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:x = np.random.uniform(0, 255, (1, height, width, 3)) - 128.\niterations = 10\nfor i in range(iterations):\nprint('Start of iteration', i)\nstart_time = time.time()\nx, min_val, info = fmin_l_bfgs_b(evaluator.loss, x.flatten(),\nfprime=evaluator.grads, maxfun=20)\nprint('Current loss value:', min_val)\nend_time = time.time()\nprint('Iteration %d completed in %ds' % (i, end_time - start_time))"}, {'role': 'assistant', 'content': 'modelling'}]