torch.triu_indices
torch.triu_indices(row, col, offset=0, *, dtype=torch.long, device='cpu', layout=torch.strided) -> Tensor
Returns the indices of the upper triangular part of a "row" by
   "col" matrix in a 2-by-N Tensor, where the first row contains row
   coordinates of all indices and the second row contains column
   coordinates. Indices are ordered based on rows and then columns.
The upper triangular part of the matrix is defined as the elements
   on and above the diagonal.
The argument "offset" controls which diagonal to consider. If
   "offset" = 0, all elements on and above the main diagonal are
   retained. A positive value excludes just as many diagonals above
   the main diagonal, and similarly a negative value includes just as
   many diagonals below the main diagonal. The main diagonal are the
   set of indices \lbrace (i, i) \rbrace for i \in [0, \min{d_{1},
   d_{2}} - 1] where d_{1}, d_{2} are the dimensions of the matrix.
Note: