code: def forward(self, dec_inp, dec_attn_mask=None, mems=None):
      output = self.dec_attn(
          dec_inp, attn_mask=dec_attn_mask, mems=mems
      )
      output = self.pos_ff(output)
  
      return output
  
imports: import sys
  import math
  import functools
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
  from proj_adaptive_softmax import ProjectedAdaptiveLogSoftmax, Projection
  from log_uniform_sampler import LogUniformSampler, sample_logits
  from fmoe import FMoETransformerMLP
label_desc: Use image node_id 2 for calling the DecoderLayer obj's underlying member method code with example usage: obj.forward(dec_inp, dec_attn_mask, mems) and returns: output