generators.ET0LTreeGrammar("tile (a)"):
  (
    { AS, BS, D },
    { startb:24, FR:2, GR:1, STile:0, empty:0 },
    {
      {
        D -> AS,
        AS -> FR[AS,BS],
        BS -> GR[BS]
      },
      {
        D -> empty,
        AS -> STile,
        BS -> STile
      }
    },
    startb[AS,AS,AS,AS,AS,D,D,D,D,D,D,D,AS,AS,AS,AS,AS,D,D,D,D,D,D,D]
  )
