code: def _skew(X, pad_value):
      """shift every row 1 step to right"""
      # X = B x M x L
      B, M, L = X.size()
      X = F.pad(X, (0, M + 1), value=pad_value)  # B x M x (L+M+1)
      X = X.view(B, -1)  # B x ML+MM+M
      X = X[:, :-M]  # B x ML+MM
      X = X.view(B, M, M + L)  # B x M x L+M
      return X
  
imports: import math
  import torch
  import torch.nn
  import torch.nn.functional
  from fairseq.modules.layer_norm import LayerNorm
  from .adaptive_span_attention import AdaptiveSpan
label_desc: Use image node_id 1 for calling a global function with example usage: _skew(X, pad_value) and returns: X