generators.ET0LTreeGrammar:
( { S0, S, A },
  { F:4, G:3, H:2, sq:0 },
  {
    {
      S0 -> F[A,A,S,S],
      S -> H[A,S],
      A -> G[A,A,A]
    },
    {
      S0 -> sq,
      S -> sq,
      A -> sq
    }
  },
  S0
)
