torch.ravel
torch.ravel(input) -> Tensor
Return a contiguous flattened tensor. A copy is made only if
   needed.
Parameters:
      input (Tensor) -- the input tensor.
Example:
  >>> t = torch.tensor([[[1, 2],
  ...                    [3, 4]],
  ...                   [[5, 6],
  ...                    [7, 8]]])
  >>> torch.ravel(t)
  tensor([1, 2, 3, 4, 5, 6, 7, 8])
