int(torch.empty((), dtype=torch.int64).random_().item())
文档里是这么描述.random_()的:
"""
random_(from=0, to=None, *, generator=None) -> Tensor
Fills :attr:`self` tensor with numbers sampled from the discrete uniform
distribution over ``[from, to - 1]``. If not specified, the values are usually
only bounded by :attr:`self` tensor's data type. However, for floating point
types, if unspecified, range will be ``[0, 2^mantissa]`` to ensure that every
value is representable. For example, `torch.tensor(1, dtype=torch.double).random_()`
will be uniform in ``[0, 2^53]``.
"""