code: def forward(self, seq, mask):
      if self.pre_mask:
          seq = self.mask_opt(seq, mask)
      seq = self.max_pool(seq)
      if self.post_mask:
          seq = self.mask_opt(seq, mask)
      return seq
  
imports: import torch
  import torch.nn.functional
  from torch import nn
  from utils import get_length, INF
label_desc: Use image node_id 2 for calling the MaxPool obj's underlying member method code with example usage: obj.forward(seq, mask) and returns: seq