generators.ET0LTreeGrammar("terdragon outline"):
(
  { S0, S },
  { I:2, T:2, line:0 },
  {
    {
      S0 -> I[S,S],
      S -> T[S,S]
    },
    {
      S0 -> line,
      S -> T[line,line]
    }
  },
  S0
)
