Mbt$
Variant of mbt that allows any non-nil value.
While mbt's guard obligation requires
the argument to be equal to t,
this variant only requires it to be iff-equivalent to t,
i.e. non-nil.
Macro: mbt$
(defmacro mbt$ (x)
(cons 'mbt
(cons (cons 'if (cons x '(t nil)))
'nil)))
