(define <grammar>
  (many1 <production>))

(define <production>
  (sequence <ident> (literal ':') <alts>))

(define <tokens>
  (many <token>))

(define <alts>
  (sequence <tokens> (many (literal '|') <tokens>)))

(define <token>
  (sequence
    (anyof '(<term>
             <ident>
             (sequence (literal '[') <tokens> (literal ']'))
             (sequence (literal '(') <alts> (literal ')') )))
    (optional (or (literal '*') (literal '+')))))

(define <ident>
  snake_case_ident)

(define <term>
  (anyof '(literal_string ALL_CAPS_TOKEN)))