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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def check(self, diff):
 r"""Check that the new file introduced has a valid name The module can either be an __init__.py file or must match ``feature_[a-zA-Z0-9_]+\.\w+``. """

        filename = pathlib.Path(diff.b_path).parts[-1]
        is_valid_feature_module_name = re_test(
            FEATURE_MODULE_NAME_REGEX, filename)
        is_valid_init_module_name = filename == '__init__.py'
        assert is_valid_feature_module_name or is_valid_init_module_name