class_docstr: Simple operator test
code: def test_func_operator(self):
      test_op = load_local_operator(
          "pytorch_object_detection_operator",
          PYTORCH_OBJECT_DETECTION_OPERATOR_PATH,
      )
      op = test_op.PyTorchObjectDetectionOperator(self.model_name)
      output = op(self.images)
      self.assertEqual(4, output[0].shape[1])
  
file_path: towhee/tests/unittests/operators/test_pytorch_object_detection_operator.py
imports: import unittest
  import torch
  import torchvision
  from pathlib import Path
  from towhee.utils.pil_utils import PILImage
  from tests.unittests.mock_operators import PYTORCH_OBJECT_DETECTION_OPERATOR_PATH, load_local_operator
label_desc: Use image node_id 2 for calling the TestOperator obj's underlying member method code with example usage: obj.test_func_operator() without return types