Rule names that occur in an element.
(element-called-rules element) → rulenames
Function:
(defun element-called-rules (element) (declare (xargs :guard (elementp element))) (element-case element :rulename (insert element.get nil) :group (alternation-called-rules element.get) :option (alternation-called-rules element.get) :char-val nil :num-val nil :prose-val nil))