code: def forward(self, a: Tensor, c: Optional[Tensor] = None):
      x = self.lin_a(a)
      if c is not None:
          x = x + self.lin_c(c).unsqueeze(1)
      x = F.elu(x)
      x = self.lin_i(x)
      x = self.dropout(x)
      x = self.glu(x)
      y = a if not self.out_proj else self.out_proj(a)
      x = x + y
      x = self.layer_norm(x)
      return x
  
imports: import torch
  import torch.nn
  import torch.nn.functional
  from torch import Tensor
  from torch.nn import LayerNorm
  import logging
  import warnings
  from typing import Tuple, Optional
  from ..losses.pytorch import MAE
  from ..common._base_windows import BaseWindows
label_desc: Use image node_id 2 for calling the GRN obj's underlying member method code with example usage: obj.forward(a, c) and returns: x