How to use the f90nml.fpy.pystr function in f90nml

if v_str == '(':
            v_re = self.token

            self._update_tokens(write_token)
            assert self.token == ','

            self._update_tokens(write_token)
            v_im = self.token

            self._update_tokens(write_token)
            assert self.token == ')'

            self._update_tokens(write_token, override)
            v_str = '({0}, {1})'.format(v_re, v_im)

        recast_funcs = [int, pyfloat, pycomplex, pybool, pystr]

        for f90type in recast_funcs:
            try:
                # Unclever hack.. integrate this better
                if f90type == pybool:
                    value = pybool(v_str, self.strict_logical)
                else:
                    value = f90type(v_str)
                return value
            except ValueError:
                continue