[{'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:def color_hist(img, nbins=32):  # Note : bins_range=(0, 256) from lecture will not work\n"""\nFunction to compute color histogram features\n"""\nchannel1_hist = np.histogram(img[:, :, 0], bins=nbins)\nchannel2_hist = np.histogram(img[:, :, 1], bins=nbins)\nchannel3_hist = np.histogram(img[:, :, 2], bins=nbins)\nhist_features = np.concatenate((channel1_hist[0], channel2_hist[0], channel3_hist[0]))\nreturn hist_features'}, {'role': 'assistant', 'content': 'data_preprocessing'}]