class_docstr: Use to replace `InputChoice` Mutable in fix process
  
  Parameters
  ----------
  mask : list
      The mask indicating which input to choose
code: def forward(self, optional_inputs):
      if len(optional_inputs) == self.mask_len:
          return optional_inputs[self.selected]
  
imports: from abc import abstractmethod
  import torch.nn
  from nni.nas.pytorch import mutables
  from nni.nas.pytorch.fixed import FixedArchitecture
  import json
  from copy import deepcopy
  import torch
  from ...model import BaseAutoModel
  from ....utils import get_logger
  from ..utils import get_hardware_aware_metric
label_desc: Use image node_id 2 for calling the FixedInputChoice obj's underlying member method code with example usage: obj.forward(optional_inputs) and returns: optional_inputs