code: def load_model_tests(
      data_dir: str = DATA_DIR,
      kind: Optional[str] = None,
  ) -> List[TestCase]:
      """Load model test cases from on-disk data files."""
      supported_kinds = os.listdir(data_dir)
      if kind not in supported_kinds:
          raise ValueError(f"kind must be one of {supported_kinds}")
  
      testcases = []
  
      kind_dir = os.path.join(data_dir, kind)
      for test_name in os.listdir(kind_dir):
          case_dir = os.path.join(kind_dir, test_name)
          # skip the non-dir files, such as generated __init__.py.
          rtol = 1e-3
          atol = 1e-7
          if not os.path.isdir(case_dir):
              continue
          if os.path.exists(os.path.join(case_dir, "model.onnx")):
              url = None
              model_name = test_name[len("test_")]
              model_dir: Optional[str] = case_dir
          else:
              with open(os.path.join(case_dir, "data.json")) as f:
                  data = json.load(f)
                  url = data["url"]
                  model_name = data["model_name"]
                  rtol = data.get("rtol", 1e-3)
                  atol = data.get("atol", 1e-7)
                  model_dir = None
          testcases.append(
              TestCase(
                  name=test_name,
                  url=url,
                  model_name=model_name,
                  model_dir=model_dir,
                  model=None,
                  data_sets=None,
                  kind=kind,
                  rtol=rtol,
                  atol=atol,
              )
          )
  
      return testcases
  
imports: import json
  import os
  from typing import List, Optional
  from onnx.backend.test.case.test_case import TestCase
label_desc: Use image node_id 1 for calling a global function with example usage: load_model_tests(data_dir, kind) and returns: testcases