new_args and new_kwargs.
  Parameters:
     **hook** (*Callable*) -- The user defined hook to be
     registered.

  Returns:
     a handle that can be used to remove the added hook by calling
     "handle.remove()"

  Return type:
     "torch.utils.hooks.RemoveableHandle"

state_dict()
  Returns the state of the optimizer as a "dict".

  It contains two entries:

  * state - a dict holding current optimization state. Its content
       differs between optimizer classes.

  * param_groups - a list containing all parameter groups where
    each
       parameter group is a dict

zero_grad(set_to_none=False)
  Sets the gradients of all optimized "torch.Tensor" s to zero.

  Parameters:
     **set_to_none** (*bool*) -- instead of setting to zero, set
     the grads to None. This will in general have lower memory
     footprint, and can modestly improve performance. However, it
