vector dimension*
  * Input2: (N, D) or (D), same shape as the Input1

  * Output: (N) or () based on input dimension. If "keepdim" is
    "True", then (N, 1) or (1) based on input dimension.

Examples::
      >>> pdist = nn.PairwiseDistance(p=2)
      >>> input1 = torch.randn(100, 128)
      >>> input2 = torch.randn(100, 128)
      >>> output = pdist(input1, input2)