message: need to append
diff: @@ -43,6 +43,7 @@ for module in cython_modules:
  include_dirs=include_dirs,
  runtime_library_dirs=runtime_library_dirs,)
  extension.cython_directives = {'language_level': str(sys.version_info[0])}
  + ext_modules.append(extension)
  ext_modules = cythonize(ext_modules)
  