torch.argsort
torch.argsort(input, dim=- 1, descending=False, stable=False) -> Tensor
Returns the indices that sort a tensor along a given dimension in
   ascending order by value.
This is the second value returned by "torch.sort()".  See its
   documentation for the exact semantics of this method.
If "stable" is "True" then the sorting routine becomes stable,
   preserving the order of equivalent elements. If "False", the
   relative order of values which compare equal is not guaranteed.
   "True" is slower.
Parameters:
      * input (Tensor) -- the input tensor.
  * **dim** (*int**, **optional*) -- the dimension to sort along

  * **descending** (*bool**, **optional*) -- controls the sorting
    order (ascending or descending)

  * **stable** (*bool**, **optional*) -- controls the relative
    order of equivalent elements

Example:
  >>> a = torch.randn(4, 4)
  >>> a
  tensor([[ 0.0785,  1.5267, -0.8521,  0.4065],
