code: def _downsample(self, planes):
      layer = self.cell_type(self.in_planes, planes, stride=2)
      self.in_planes = planes
      return layer
  
imports: import torch
  import torch.nn
  import torch.nn.functional
label_desc: Use image node_id 3 for calling the PNASNet obj's underlying member method code with example usage: obj._downsample(planes) and returns: layer