def METHOD_NAME(self) -> None:
    """This function checks for duplicate value generators."""
    all_python_files = self.get_all_python_files()
    all_value_generators = []
    for file_name in all_python_files:
        python_module = importlib.import_module(file_name)
        for name, clazz in inspect.getmembers(
                python_module, predicate=inspect.isclass):
            all_base_classes = [base_class.__name__ for base_class in
                                (inspect.getmro(clazz))]
            # Check that it is a subclass of 'BaseValueGenerator'.
            if 'BaseValueGenerator' in all_base_classes:
                all_value_generators.append(name)
    expected_value_generators = ['BaseValueGenerator', 'Copier',
                                 'RandomSelector']
    self.assertEqual(
        sorted(all_value_generators), sorted(expected_value_generators))