Tree matching theorem for parse-wsp/vchar.
Theorem:
(defthm tree-match-of-parse-wsp/vchar (b* (((mv error? tree? &) (parse-wsp/vchar input))) (implies (and (not error?) (equal element (!_ (/_ *wsp*) (/_ *vchar*)))) (tree-match-element-p tree? element *grammar*))))