ConstantPad1d
class torch.nn.ConstantPad1d(padding, value)
Pads the input tensor boundaries with a constant value.
For N-dimensional padding, use "torch.nn.functional.pad()".
Parameters:
      padding (int, tuple) -- the size of the padding. If is
      int, uses the same padding in both boundaries. If a 2-tuple,
      uses (\text{padding_left}, \text{padding_right})
Shape:
      * Input: (C, W_{in}) or (N, C, W_{in}).
  * Output: (C, W_{out}) or (N, C, W_{out}), where

    W_{out} = W_{in} + \text{padding\_left} +
    \text{padding\_right}

Examples:
  >>> m = nn.ConstantPad1d(2, 3.5)
  >>> input = torch.randn(1, 2, 4)
  >>> input
  tensor([[[-1.0491, -0.7152, -0.0749,  0.8530],
           [-1.3287,  1.8966,  0.1466, -0.2771]]])
  >>> m(input)
  tensor([[[ 3.5000,  3.5000, -1.0491, -0.7152, -0.0749,  0.8530,  3.5000,
             3.5000],
