A Function that Makes Closures

> (defun make-toggle (on-value off-value)

(let ((bit 0))

#'(lambda ()

(setq bit (- 1 bit))

(if (= bit 1) on-value off-value)

) ) )

MAKE-TOGGLE

> (setq traffic-light

(make-toggle 'green 'red) )

#<Interpreted Closure (unnamed) @ #x204c8fcb>

> (funcall traffic-light)

RED

> (funcall traffic-light)

GREEN

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