void dotDependenciesString(StringBuilder s, Set<Node> used) {
        if (used.contains(this))
            return;
        used.add(this);

        for (Node afterNode : nodesAfterThis) {
            String indent = "    ";
            s.append(indent);
            s.append(dotName()).append(" -> ").append(afterNode.dotName())
                    .append('\n');
            afterNode.dotDependenciesString(s, used);
        }
    }
A node in a dependency graph.

Dependencies must declared as follows:
    a.before(b) , where a,b are nodes.

The following dependencies are currently allowed:
    searcher.before(name)
    name.before(searcher)
    searcher1.before(searcher2)

 Where name designates a NameProvider( either a phase or a set of searchers).

@author Tony Vaagenes
container-core/src/main/java/com/yahoo/component/chain/dependencies/ordering/Node.java