generators.BSTGrammar:
( { S, A },
  { a:0, b:0, c:1, h:2, v:2 },
  { 1, 2},
  1,
  {
    { A -> h[A<1>,A<2>]  } weight 2,
    { A -> v[A<1>,A<2>]  } weight 2,
    { A -> c[A<1>] } weight 2,
    { A -> a },
    { A -> b }
  },
  h[A<1>,A<1>] )  