(pr-stash '(totruep (prop ↑setof $x $p $s) truep-setof)) (defun truep-setof (p) (cond ((unvarp (cadddr p)) (do ((l (trueps (caddr p)) (cdr l)) (x (cadr p)) (nl)) ((null l) (pset (cadddr p) nl truth)) (setq nl (cons (plug x (car l)) nl))))))