ELEMENT-OF
==========

Syntax: (element-of <bql-var>
          {<evaluates-to-list> | <bql-var>})

The operator ELEMENT-OF binds values to BQL-
variables. It can only be used in combination
with an ASK-expression.

Example: >(ask [and (element-of _x '(3 2 1))
                      (< _x 2)]
               (kb-format "~A" _x))
         1
         NIL

ELEMENT-OF sequentially binds 3, 2 and 1 to _x