$ go get github.com/quincy/etime

$ etime --help
usage: etime [-h] {timespec}

-h, --help   prints this message
timespec     is a string representation of a time to convert in one of the following formats:
        [Unix epoch time]
        Mon Jan _2 15:04:05 2006
        Mon Jan _2 15:04:05 MST 2006
        Mon Jan 02 15:04:05 -0700 2006
        02 Jan 06 15:04 MST
        02 Jan 06 15:04 -0700
        Monday, 02-Jan-06 15:04:05 MST
        Mon, 02 Jan 2006 15:04:05 MST
        Mon, 02 Jan 2006 15:04:05 -0700
        2006-01-02T15:04:05Z07:00
        2006-01-02T15:04:05.999999999Z07:00
        3:04PM
        Jan _2 15:04:05
        Jan _2 15:04:05.000000000
        Jan _2 15:04:05.000
        Jan _2 15:04:05.000000