generators.ET0LTreeGrammar("dragon outline"):
( { S0, S, A },
  { line:0, F:2, G:2, I:2 },
  {
    { 
      S0 -> I[S,A],
      S  -> F[S,A],
      A  -> G[S,S]
   },
  { 
      S0 -> line,
      S  -> F[line,line],
      A  -> G[line,line]
     }
  },
  S0 )
