sum(tensor, tensor) =tensor + tensor

>>> a=torch.randn(1,1,2,2)
>>> a
tensor([[[[-0.5695, -0.8966],
          [-0.0143,  0.9773]]]])
>>> b=torch.randn(1,1,2,2)
>>> b
tensor([[[[-1.4048,  0.9351],
          [ 1.6179, -0.8116]]]])
>>> sum(a,b)
tensor([[[[-1.9743,  0.0385],
          [ 1.6037,  0.1657]]]])
>>> a
tensor([[[[-0.5695, -0.8966],
          [-0.0143,  0.9773]]]])
>>> b
tensor([[[[-1.4048,  0.9351],
          [ 1.6179, -0.8116]]]])
>>> a+b
tensor([[[[-1.9743,  0.0385],
          [ 1.6037,  0.1657]]]])