============================================
Grammar
============================================

G1 {}
G2 <: G1 {}
G3 {
}

---

(source_file
  (grammar
    name: (identifier)
    body: (grammar_body))
  (grammar
    name: (identifier)
    inherits: (super_grammar
      name: (identifier))
    body: (grammar_body))
  (grammar
    name: (identifier)
    body: (grammar_body)))
