if (i1 > i2) { int tmp = i1; i1 = i2; i2 = tmp; }
    vDescriptor function(vDescriptor[] args) {	vCset c = vCset.argVal(args, 0);	vString s = iRuntime.argSubject(args, 1);	int i1 = s.posEq(iRuntime.argPos(args, 2));	int i2 = s.posEq(vInteger.argVal(args, 3, 0));	if (i1 < i2 && c.member(s.value.charAt(i1-1))) {	    return iNew.Integer(i1+1);	}	return null;    }