public <S> GraphTraversal<S, S> call() {
        final GraphTraversalSource clone = this.clone();
        clone.gremlinLang.addStep(GraphTraversal.Symbols.call);
        final GraphTraversal.Admin<S, S> traversal = new DefaultGraphTraversal<>(clone);
        return traversal.addStep(new CallStep<>(traversal, true));
    }
Spawns a {@link GraphTraversal} starting with a list of available services.

@since 3.6.0
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/dsl/graph/GraphTraversalSource.java