COND
====

syntax: (cond {(<test> {<form> ...}) ...})

This function evaluates the testforms sequentially,
until one of them has a value different to NIL. Then
the following forms <form> will be evaluated and the
value of the last form will be returned by cond. If
all testforms return NIL, then cond will return NIL
too.

example:       >(setq a nil)
               NIL
               >(setq b nil)
               NIL
               >(setq c 3)
               100
               >(cond (a 1) (b 2) (c 3))
               3