How to use the pyrfc.ExternalRuntimeError function in pyrfc

elif REQUTEXT == 'EXCEPTION_MESSAGE':
        raise ABAPApplicationError(key='BAD_EXCEPTION_W_MSG',
            msg_class='SR', # message id or class
            msg_type='E', # out of e.g. 'E', 'A' or 'X'
            msg_number='007', # 3 char numeric
            msg_v1='V1 text' # 50 char
        )
    elif REQUTEXT == 'MESSAGE':
        raise ABAPRuntimeError(
            msg_class='SM', # message id or class
            msg_type='E', # out of e.g. 'E', 'A' or 'X'
            msg_number='107', # 3 char numeric string
            msg_v1='V1 text (ABAP_MESSAGE)'
        )
    elif REQUTEXT == 'FAILURE':
        raise ExternalRuntimeError("Something very bad happened.")
    elif REQUTEXT == 'INVALID':
        raise RFCError("Invalid exception")
    return {
        'ECHOTEXT': REQUTEXT,
        'RESPTEXT': u"Local (raise error) server here. Use the following values"
                    u"for REQUTEXT: EXCEPTION, EXCEPTION_MESSAGE, MESSAGE, "

self.assertEqual(run.exception.msg_v1, "V1 text")

        with self.assertRaises(ABAPRuntimeError) as run:
            test.invoke_srv_function("STFC_CONNECTION", REQUTEXT="MESSAGE")
        self.assertEqual(run.exception.code, 4, "rc")
        self.assertEqual(run.exception.msg_class, "SM")
        self.assertEqual(run.exception.msg_type, "E")
        self.assertEqual(run.exception.msg_number, "107")
        self.assertEqual(run.exception.msg_v1, "V1 text (ABAP_MESSAGE)")

        with self.assertRaises(ExternalRuntimeError) as run:
            test.invoke_srv_function("STFC_CONNECTION", REQUTEXT="FAILURE")
        self.assertEqual(run.exception.code, 15, "rc")
        self.assertEqual(run.exception.message[:9], "Something")

        with self.assertRaises(ExternalRuntimeError) as run:
            test.invoke_srv_function("STFC_CONNECTION", REQUTEXT="INVALID")
        self.assertEqual(run.exception.code, 15, "rc")
        self.assertEqual(run.exception.message[:7], "Invalid")

def test_ping(self):
        assert self.conn.alive
        self.conn.ping()
        self.conn.close()
        try:
            self.conn.ping()
        except pyrfc.ExternalRuntimeError as ex:
            error = get_error(ex)
            assert error["code"] == 13
            assert error["key"] == "RFC_INVALID_HANDLE"
            assert (
                error["message"][0]
                == "An invalid handle 'RFC_CONNECTION_HANDLE' was passed to the API call"
                or error["message"][0] == "An invalid handle was passed to the API call"
            )

def test_non_existing_field_table(self):
        IMPORTSTRUCT = {"XRFCCHAR1": "A", "RFCCHAR2": "BC", "RFCCHAR4": "DEFG"}
        try:
            result = self.conn.call("STFC_STRUCTURE", RFCTABLE=[IMPORTSTRUCT])
        except pyrfc.ExternalRuntimeError as ex:
            assert ex.code == 20
            assert ex.key == "RFC_INVALID_PARAMETER"
            assert ex.message == "field 'XRFCCHAR1' not found"