how to expand the dimensions of a tensor in pytorch
i'm a newcomer for pytorch. if i have a tensor like that:

A = torch.tensor([[1, 2, 3], [ 4, 5, 6]]),

but my question is how to get a 2 dimensions tensor like:
B =  Tensor([[[1, 2, 3],
                           [4, 5, 6]], 

                          [[1, 2, 3], 
                           [4, 5, 6]]])


You can concatenate ...
A
tensor([[[1., 2., 3.],
         [4., 5., 6.]]])
B = torch.cat((a, a))

B
tensor([[[1., 2., 3.],
         [4., 5., 6.]],

        [[1., 2., 3.],
         [4., 5., 6.]]])

