what does clamp_ does in pytorch and how to change it to the tensorflow 2.0?
   prior_boxes = torch.FloatTensor(prior_boxes).to(device)  # (8732, 4)
   prior_boxes.clamp_(0, 1)  # (8732, 4)


what dooes clamp_ do in pytorch and how to change it to the tensorflow 2.0?
I'm not sure what clamp_ do exactly? 

clamp_(0, 1) Clamp all elements in prior_boxes into the range [ 0, 1].

Tensorflow:

tf.clip_by_value
https://www.tensorflow.org/api_docs/python/tf/clip_by_value
