[{'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:param_lgb = param_grid = [{\n    'n_estimators': [400, 700, 1000], \n    'max_depth': [15,20,25],\n    'num_leaves': [50, 100, 200],\n    'min_split_gain': [0.3, 0.4],\n}]"}, {'role': 'assistant', 'content': 'modelling'}]