````python if params['is_use_dnn_part']: w_fm_nn_input = tf.reshape(tf.gather(w_fm, _ind) * tf.expand_dims(_values, 1), [-1, field_cnt * dim]) print(w_fm_nn_input.shape) ```` 这段代码实现了什么逻辑? field_cnt和feature_cnt有什么差别? 谢谢!!