struct a end;

method even()
	if this.a = 0 then
		return 0;
	else
		this.a := this.a - 1;
		return odd();
	end;
end;

method odd()
	if 0 = this.a then
		return 1;
	else
		this.a := this.a - 1;
		return even();
	end;
end;