使用 GridSearchCV 构建模型后，使用 model.cv_results_ 获得交叉验证结果。但在结果中，有一个参数让我感到困惑。是什么rank_test_score代表在这？
mean_fit_time 0.00265972
std_fit_time 0.000466648
mean_score_time 0.00133236
std_score_time 0.000470977
param_n_neighbors 1
param_weights distance
params {'n_neighbors': 1, 'weights': 'distance'}
split0_test_score 0.70405
split1_test_score 0.73125
split2_test_score 0.69906
mean_test_score 0.711458
std_test_score 0.0141423
rank_test_score 1
split0_train_score 1
split1_train_score 1
split2_train_score 1
mean_train_score 1
std_train_score 0
Name: 1, dtype: object