Maybe this is a silly question, but how can we sum over multiple dimensions in pytorch?
In numpy, np.sum()  takes a axis argument which can be an int or a tuple of ints, while in pytorch, torch.sum() takes a dim argument which can take only a single int.
Say I have a tensor of size 16 x 256 x 14 x 14, and I want to sum over the third and fourth dimensions to get a tensor of size 16 x 256. In numpy, one can do np.sum(t, axis=(2, 3)), what is the pytorch equivalent?