code: def test_collate_fn():
      test_input = [(1, 10), (2, 20), (3, 30)]
      test_output = DataLoader.collate_data(test_input)
  
      assert isinstance(test_output, tuple)
      assert len(test_output) == 2
      assert isinstance(test_output[0], list)
      assert len(test_output[0]) == 3
  
      assert test_output[0][0] == 1
      assert test_output[0][2] == 3
      assert test_output[1][0] == 10
      assert test_output[1][2] == 30
  
file_path: detecto/detecto/tests/test_core.py
imports: import torch
  from detecto.core import *
  from detecto.utils import read_image
  from .helpers import get_dataset, get_image, get_model, empty_predictor
  from torchvision import transforms
  from torchvision.models.detection.faster_rcnn import FastRCNNPredictor
label_desc: Use image node_id 2 for calling a global function with example usage: test_collate_fn() without return types