drop operator =  (rational, rational);
drop operator <> (rational, rational);
drop operator +  (rational, rational);
drop operator -  (rational, rational);
drop operator *  (rational, rational);
drop operator /  (rational, rational);
drop operator >  (rational, rational);
drop operator >= (rational, rational);
drop operator <  (rational, rational);
drop operator <= (rational, rational);
drop function eq(rational, rational);
drop function ne(rational, rational);
drop function gt(rational, rational);
drop function ge(rational, rational);
drop function lt(rational, rational);
drop function le(rational, rational);
drop function add(rational, rational);
drop function sub(rational, rational);
drop function mult(rational, rational);
drop function div(rational, rational);
drop type rational;
drop function rational_in(opaque);
drop function rational_out(opaque);