Examples:
  >>> m = nn.ReplicationPad3d(3)
  >>> input = torch.randn(16, 3, 8, 320, 480)
  >>> output = m(input)
  >>> # using different paddings for different sides
  >>> m = nn.ReplicationPad3d((3, 3, 6, 6, 1, 1))
  >>> output = m(input)
