golang time and duration

package mainimport "fmt"import "time"func main() {    p := fmt.Println    // We'll start by getting the current time.    now := time.Now()    p("time.Now(): ", now)    // You can build a "time" struct by providing the    // year, month, day, etc. Times are always associated    // with a "Location", i.e. time zone.    then := time.Date(2009, 11, 17, 20, 34, 58, 651387237, time.UTC)    p("time.Date(): ", then)    p("==================================")    // You can extract the various components of the time    // value as expected.    p("time.Date().Year(): ", then.Year())    p("time.Date().Month(): ", then.Month())    p("time.Date().Day(): ", then.Day())    p("time.Date().Hour(): ", then.Hour())    p("time.Date().Minute(): ", then.Minute())    p("time.Date().Second(): ", then.Second())    p("time.Date().Nanosecond(): ", then.Nanosecond())    p("time.Date().Location(): ", then.Location())    // The Monday-Sunday "Weekday" is also available.    p("time.Date().Weekday(): ", then.Weekday())    p("==================================")    // These methods compare two times, testing if the    // first occurs before, after, or at the same time    // as the second, respectively.    p("time.Date().Before(now): ", then.Before(now))    p("time.Date().After(now): ", then.After(now))    p("time.Date().Equal(now): ", then.Equal(now))    p("==================================")    // The "Sub" methods returns a "Duration" representing    // the interval between two times.    diff := now.Sub(then)    p("time.Now().Sub(time.Date()): ", diff)    p("==================================")    // We can compute the length of the duration in    // various units.    p("time.Date().Sub(then).Hours(): ", diff.Hours())    p("time.Date().Sub(then).Minutes(): ", diff.Minutes())    p("time.Date().Sub(then).Seconds(): ", diff.Seconds())    p("time.Date().Sub(then).Nanoseconds(): ", diff.Nanoseconds())    p("==================================")    // You can use "Add" to advance a time by a given    // duration, or with a "-" to move backwards by a    // duration.    p("time.Date().Sub(now).Add(now.Sub(then)): ", now.Add(diff))    p("time.Date().Sub(then).Add(-(now.Sub(then))): ", then.Add(-diff))}