In tutorials, we can run the code as follow and have result:
x = torch.ones(2, 2, requires_grad=True)
print(x)
tensor([[1., 1.],
[1., 1.]], requires_grad=True)
y = x + 2
print(y)
tensor([[3., 3.],
[3., 3.]], grad_fn=)
print(y.grad_fn)
<AddBackward0 object at 0x7f1b248453c8>
However, I don’t kown the meaning of 0x7f1b248453c8, who could tell me how  0x7f1b248453c8 woks.
Thank you !