trick

uint.go

package main

import "fmt"

type Year uint
type Month uint

func (year Year) isLeap() bool {
	return ((year%4 == 0) && (year%100 != 0)) || (year%400 == 0)
}

func (year Year) days() uint {
	if year.isLeap() {
		return 366
	} else {
		return 365
	}
}

func (month Month) days() uint {
	return []uint{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}[month]
}

func main() {
	fmt.Printf("year 2014 has %d days.\n", Year(3).days())
	fmt.Printf("month 11  has %d days.\n", Month(11).days())
}