Clive, 2nd ed. User's manual. Section 2 
SYNOPSYS

import "clive/u/user"

const Idle = State(iota) ...
var IdleIval = 30 * time.Second ...
func Becomes() (<-chan State, error)
func IdleFor(d time.Duration) <-chan error
func IdleTime() (time.Duration, error)
func Wakeup() <-chan error
type State int

DESCRIPTION

User events. Currently works only for osx but it should be trivial to fix it
to work on other systems as well.

CONSTANTS

const (
	Idle  = State(iota) // user is idle for more than IdleIVal seconds
	Busy                // user ceases being idle
	Awake               // user terminal wake up from sleep
)

TYPES

type State int
    User states

func (i State) String() string

FUNCTIONS

func Becomes() (<-chan State, error)
    Notify through the chan returned when the user becomes idle, ceases being
    idle or resumes after a sleep. Upon errors the channel is closed.

func IdleFor(d time.Duration) <-chan error
    Notify through the chan returned when the user is idle for more than the
    given duration. If there's any error the chan is notified with the error
    indication, a null error is sent otherwise.

func IdleTime() (time.Duration, error)
    Return the duration for user idleness, if it's more than one day, one day is
    reported.

func Wakeup() <-chan error
    Close the returned channel when the terminal resumes from sleep.

VARIABLES

var (
	IdleIval = 30 * time.Second // user is idle if quiet for more than this.
	PollIval = 5 * time.Second  // freq. to poll user for idleness
)

User's manual, 2nd ed. Section 2