/* fibonacci */

/* F_0 = 0 */
/* F_1 = 1 */
/* F_n = F_{n-1} + F_{n-2} */

method fib(x)
	var a := 0;
	var b := 1;
	var c := x;
	while not (x < 2)
	do
		var A := a;
		var B := b;
		a := B;
		b := A-(0-B);
		c := b;
		x := x-1;
	end;
	return c;
end;