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#### 25.2.4 sleep [Function]

`sleep` seconds ⇒ nil

#### Arguments and Values::

seconds—a non-negative real.

#### Description::

Causes execution to cease and become dormant for approximately the seconds of real time indicated by seconds, whereupon execution is resumed.

#### Examples::

     (sleep 1) ⇒  NIL

    ;; Actually, since SLEEP is permitted to use approximate timing,
    ;; this might not always yield true, but it will often enough that
    ;; we felt it to be a productive example of the intent.
     (let ((then (get-universal-time))
           (now  (progn (sleep 10) (get-universal-time))))
       (>= (- now then) 10))
    ⇒  true

#### Side Effects::

Causes processing to pause.

#### Affected By::

The granularity of the scheduler.

#### Exceptional Situations::

Should signal an error of type type-error if seconds is not a non-negative real.