void red(unsigned long d) {
  digitalWrite(3, HIGH);
  delay(d);
  digitalWrite(3, LOW);
}

void green(unsigned long d) {
  digitalWrite(2, HIGH);
  delay(d);
  digitalWrite(2, LOW);
}

void blink(void userfunc(unsigned long), unsigned long d) {
  userfunc(d);
}

void setup() {
  pinMode(2, OUTPUT);
  pinMode(3, OUTPUT);
}

void loop() {
  blink(red,250);
  blink(green,750);
}