ex) 

CREATE TYPE a AS (z varchar(20))

METHOD foo(i integer) RETURNS varchar(80)

LANGUAGE SQL;

CREATE TYPE b UNDER a AS (y varchar(20))

OVERRIDING METHOD foo(i integer) RETURNS varchar(80);

CREATE TYPE c UNDER a AS (x varchar(20))

OVERRIDING METHOD foo(i integer) RETURNS varchar(80);

CREATE TYPE d UNDER b AS (w varchar(20))

OVERRIDING METHOD foo(i integer) RETURNS varchar(80);

CREATE METHOD foo(i integer) FOR a

RETURN "In method foo_a. Input: " | char(i) | self..z | ".";

CREATE METHOD foo(i integer) FOR b

RETURN "In method foo_b. Input: " | char(i) | self..z |

" y = " | self..y | ".";

CREATE METHOD foo(i integer) FOR c

RETURN "In method foo_c. Input: " | char(i) | self..z |

" y = " | self..y | " x = " | self..x | ".";

CREATE METHOD foo(i integer) FOR d

RETURN "In method foo_d. Input: " | char(i) | self..z |