generators.ET0LTreeGrammar:
  ( { A, B, Af, Bf },
    { scale.3333:5, scale1.73205:1, scale3:1, 3+:1, 2+:2, 3-:1, 2-:2, F:0, fill.8-.3-.1:3 },
    {
      {
        A -> scale.3333[2+[B,Af],Af,2-[Af,3-[scale1.73205[Bf]]],B,Af],
        B -> scale.3333[2-[A,Bf],Bf,2+[Bf,3+[scale1.73205[Af]]],A,Bf],
        Af -> scale.3333[A,Bf,2+[3+[scale1.73205[B]],A],A,2-[A,Bf]],
        Bf -> scale.3333[B,Af,2-[3-[scale1.73205[A]],B],B,2+[B,Af]]
      },
      {
        A -> scale.3333[A,Bf,2+[3+[scale1.73205[B]],A],A,2-[A,Bf]],
        B -> scale.3333[B,Af,2-[3-[scale1.73205[A]],B],B,2+[B,Af]],
        Af -> scale.3333[2+[B,Af],Af,2-[Af,3-[scale1.73205[Bf]]],B,Af],
        Bf -> scale.3333[2-[A,Bf],Bf,2+[Bf,3+[scale1.73205[Af]]],A,Bf]
      },
      {
        A -> F,
        B -> F,
        Af -> F,
        Bf -> F
      }
    },
    fill.8-.3-.1[3+[F],scale3[A],3-[F]]
  )
