class_docstr: PositionalEncoding layer for a given Transformer model.
class_docstr_tok: ["PositionalEncoding","layer","for","a","given","Transformer","model","."]
code: def forward(self, x):
      x = x + self.pe[: x.size(0), :]
      return self.dropout(x)
  
imports: import math
  import torch
  import torch.nn
  from fairscale.nn.moe.moe_layer import MOELayer
  from fairscale.nn.moe.top2gate import Top2Gate
label_desc: Use image node_id 2 for calling the PositionalEncodingLayer obj's underlying member method code with example usage: obj.forward(x) and returns: self