A variation on the
assert' macro in which the restart handler is bound<br> during the execution of the test-form, so that uses of this macro can be nested.<br> As with assert,' a setf-able
place' may be given, but unlike assert,' only
one may be given. As with
assert,' you can give an error message, but you can<br> also give a message to go in the restart handler. That report message may also<br> use the arguments. It will usually say something like
supply a new value for<br> foo.'' The restart is named continue,' and takes one argument, the value to
place' to. Like assert,' NIL is returned if test-form is true.