class_docstr: Construct a layernorm module (See citation for details).
code: def forward(self, x):
      mean = x.mean(-1, keepdim=True)
      std = x.std(-1, keepdim=True)
      return self.a_2 * (x - mean) / (std + self.eps) + self.b_2
  
imports: import copy
  import math
  import paddle
  import paddle.nn
  import paddle.nn.functional
label_desc: Use image node_id 2 for calling the LayerNorm obj's underlying member method code with example usage: obj.forward(x) and returns: unknown