Availability:built-in
sleep(+Time)Suspend execution Time seconds. Time is either a
floating point number or an integer. Granularity is dependent on the
system's timer granularity. A negative time causes the timer to return
immediately. On most non-realtime operating systems we can only ensure
execution is suspended for at least Time seconds.
On Unix systems the sleep/1
predicate is realised ---in order of preference--- by nanosleep(),
usleep(), select() if the time is below 1 minute, or sleep(). On Windows
systems Sleep() is used.