code: public int compareTo(final Vertex<T> o)
      {
          int orderInd;
  
          if (m_order < o.m_order)
          {
              orderInd = -1;
          }
          else if (m_order > o.m_order)
          {
              orderInd = 1;
          }
          else
          {
              orderInd = 0;
          }
  
          return orderInd;
      }
docs: Used in the sort algorithm to sort all the Vertices so that they respect
  the ordinal they were given during the topological sort.
  
  @param o  The other Vertex to compare with
  @return -1 if this < o, 0 if this == o, or 1 if this > o