func.getNumArguments());
  auto graph_op = cast<GraphOp>(func.front().front());

  auto fetch = graph_op.GetFetch();
  OpBuilder builder_chain_src(fetch);
  builder_chain_src.setInsertionPointToStart(fetch->getBlock());

  OpBuilder builder_chain_sink(fetch);
  int chain_index = num_old_outputs;

  // Iterate over all equivalence classes.