code: def find_fixtures(fixtures_base_dir: str) -> Iterable[Tuple[str, str]]:
      
      all_fixture_paths = find_fixture_files(fixtures_base_dir)
  
      for fixture_path in sorted(all_fixture_paths):
          with open(fixture_path) as fixture_file:
              fixtures = json.load(fixture_file)
  
          for fixture_key in sorted(fixtures.keys()):
              yield (fixture_path, fixture_key)
docs: Finds all of the (fixture_path, fixture_key) pairs for a given path under
      the JSON test fixtures directory.