public static <N> ImmutableGraph<N> transitiveClosure(
      Graph<N> graph, TransitiveClosureSelfLoopStrategy strategy) {
    ImmutableGraph.Builder<N> transitiveClosure =
        GraphBuilder.from(graph).allowsSelfLoops(true).<N>immutable();

    for (N node : graph.nodes()) {
      // add each node explicitly to include isolated nodes
      transitiveClosure.addNode(node);

import static com.google.common.graph.Graphs.copyOf;
import static com.google.common.graph.Graphs.inducedSubgraph;
import static com.google.common.graph.Graphs.transitiveClosure;
import static com.google.common.graph.Graphs.transpose;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.common.collect.ImmutableSet;