   
   
   
-  // A graph's size is |E|, the number of edges
+  /// return the graph's size, |E|, i.e. the number of edges
   
   func size() -> Int
   {
     return self.edges.count
   }
+  
+  
+  /// Add the given vertice to the graph
   
   func addVertice(x: SPTVertice)
   {

  }
  
  
  
  /// Will first verify that
  ///
  ///  - there isn't already an edge between the two vertices between adding one

  }
  
  
  
  // Return all vertices y such as
  //
  //  - there is an edge from x to y or 
  //  - there is an edge from y to x.
  
  func neighbors(x: SPTVertice) -> SPTVertice[]
  {
