def METHOD_NAME(self):
    def fn(a: str, b: str):
        """My fn.
        Args:
            a (str): String a.
            b (str): String b.
        Returns:
            str: Concat str.
        """
        return a + b
    a_descr = parsing.get_param_descr(fn, 'a')
    self.assertEqual(a_descr, 'String a.')
    b_descr = parsing.get_param_descr(fn, 'b')
    self.assertEqual(b_descr, 'String b.')