code: private static final LongArrayList toLongList(List<TitanVertex> vertices) {
          LongArrayList result = new LongArrayList(vertices.size());
          for (TitanVertex n : vertices) {
              result.add(n.longId());
          }
          return result;
      }
docs: Utility method used to convert the list of vertices into a list of vertex ids (assuming all vertices have ids)
  
  @param vertices
  @return