return
				}
				if f(v) {
					r <- v
				}
			}
		}
	}(ctx, c, f, r)
	return r
}

// _Sink returns a channel that discards all values sent to it.
// This will leave a goroutine running until the context is canceled
// or the returned channel is closed.
func _Sink[Elem any](ctx context.Context) chan<- Elem {
	r := make(chan Elem)
	go func(ctx context.Context, r <-chan Elem) {
		for {

  if (ctrl_edges.empty()) {
    return;
  }

  if (ctrl_edges.size() == 1 && ctrl_edges.front()->dst()->IsSink()) {
    // Avoid creating a Merge node if we can just add an edge to _SINK
    // instead.
    s.graph()->AddControlEdge(new_node, s.graph()->sink_node());
    return;
  }

  // We can't merge control edges directly so we instead first "convert" them to

  for (Operation& inst : graph_op.GetBody()) {
    TF_RETURN_IF_ERROR(exporter.AddEdge(&inst));
  }
  // Fixes the edges between the inserted nodes and special "_SOURCE" and
  // "_SINK".
  FixupSourceAndSinkEdges(graph.get());

  FixupInputNamesFromEdges(graph.get());

  TF_RETURN_IF_ERROR(
      exporter.GetControlRetNodes(graph_op.GetFetch(), control_ret_nodes));

  return graph;
}

  for (Operation& inst : graph_op.GetBody()) {
    TF_RETURN_IF_ERROR(exporter.AddEdge(&inst));
  }
  // Fixes the edges between the inserted nodes and special "_SOURCE" and
  // "_SINK".
  FixupSourceAndSinkEdges(graph.get());

  FixupInputNamesFromEdges(graph.get());

  TF_RETURN_IF_ERROR(
      exporter.GetControlRetNodes(graph_op.GetFetch(), control_ret_nodes));

  return graph;
}

  // particularly seems to be the case for the control edges between _SOURCE
  // and _SINK that the Graph constructor inserts. Copy the input edges and
  // sort the edges, but only the control edges, not data edges!
  // TODO(jmolloy): We should probably just ignore _SOURCE and _SINK nodes.
  // They'll break roundtripping anyway unless we strip them when converting
  // back to graphdef.