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