Returns:
      A tensor of shape equal to the broadcasted shape of "condition",
      "input", "other"
Return type:
      Tensor
Example:
  >>> x = torch.randn(3, 2)
  >>> y = torch.ones(3, 2)
  >>> x
  tensor([[-0.4620,  0.3139],
          [ 0.3898, -0.7197],
          [ 0.0478, -0.1657]])
  >>> torch.where(x > 0, x, y)
  tensor([[ 1.0000,  0.3139],
          [ 0.3898,  1.0000],
          [ 0.0478,  1.0000]])
  >>> x = torch.randn(2, 2, dtype=torch.double)
  >>> x
  tensor([[ 1.0779,  0.0383],
          [-0.8785, -1.1089]], dtype=torch.float64)
  >>> torch.where(x > 0, x, 0.)
  tensor([[1.0779, 0.0383],
          [0.0000, 0.0000]], dtype=torch.float64)

torch.where(condition) -> tuple of LongTensor
"torch.where(condition)" is identical to "torch.nonzero(condition,
   as_tuple=True)".
Note:
 See also "torch.nonzero()".
