   
   
   
-  // the order of a graph is |V| (the number of vertices)
+  /// return the order of a graph, |V|, i.e. the number of vertices
   
   func order() -> Int
   {

  }
  
  
  
  func neighbors(x: SPTVertice) -> SPTVertice[]
  {

  }
  
  
  /// Return true if the graph contains the given vertice
  ///
  /// this is certainly not optimal but for the moment being
  /// we are seeking robustness more than efficiency
  
