Takes care of modifying the edge and vertices so they refer to each other correctly. Counts and returns the total number of vertices in a graph. Returns nil if there is no edge connecting them. Returns the edges leaving this vertex. Counts and returns the total number of edges in a graph.
Exceptions There are also a number of standard exceptions that can be raised.
Especially useful in search functions. The first parameter graph is an adjacency list which is filled. The task is to find the shortest path from any vertex of this graph to any other vertex. To do this we fill a data structure which is used to trace the shortest path from any vertex to any other vertex of this graph without the need to search. The second parameter trace-graph is the data structure that serves this purpose.