Disambiguation between c-wsp and any of "=" and "=/".
Theorem: fail-cwsp-when-match-equal-/-equal-slash
(defthm fail-cwsp-when-match-equal-/-equal-slash (implies (tree-match-element-p tree (!_ (/_ "=") (/_ "=/")) *grammar*) (mv-nth 0 (parse-cwsp (append (tree->string tree) rest-input)))))