generators.ET0LTreeGrammar("striped dragon"):
  ( { A, B },
    { F:0, f:0, +:1, 4+:1, -:1, conc:2, hide:1 },
    {
      {
        A -> (-[A] conc +[B]),
        B -> (+[A] conc -[B])
      },
      {
        A -> F,
        % Note: f is a synonym for hide[F].
        B -> f
      }
    },
    A
  )
