code: def __route_layer(
      self, y1: torch.Tensor, y2: Optional[torch.Tensor] = None
  ) -> torch.Tensor:
      if isinstance(y2, torch.Tensor):
          return torch.cat([y1, y2], 1)
      return y1
  
file_path: ImageAI/imageai/yolov3/tiny_yolov3.py
imports: from typing import Union, List, Tuple, Optional
  import torch
  import torch.nn
  import numpy
  from .yolov3 import DetectionLayer, ConvLayer
label_desc: Use image node_id 3 for calling the YoloV3Tiny obj's underlying member method code with example usage: obj.__route_layer(y1, y2) and returns: y1, torch