---- G ----
digraph {
  /* 6 edges */
  A -> B;
  A -> C;
  B -> C;
  B -> X;
  C -> A;
  X -> Y;
}

---- tc(G) ----
digraph {
  /* 16 edges */
  A -> A;
  A -> B;
  A -> C;
  A -> X;
  A -> Y;
  B -> A;
  B -> B;
  B -> C;
  B -> X;
  B -> Y;
  C -> A;
  C -> B;
  C -> C;
  C -> X;
  C -> Y;
  X -> Y;
}

---- slow_tc(G) ----
digraph {
  /* 16 edges */
  A -> A;
  A -> B;
  A -> C;
  A -> X;
  A -> Y;
  B -> A;
  B -> B;
  B -> C;
  B -> X;
  B -> Y;
  C -> A;
  C -> B;
  C -> C;
  C -> X;
  C -> Y;
  X -> Y;
}