method f1(a b) return a - (-1 * b); end; method f2(a b) return a - (-2 * b); end; method f4(a b) return a - (-4 * b); end; method f8(a b) return a - (-8 * b); end; method f(a b c d) return a - (-8 * (b - (-4 * (c - (-2 * d))))); end;