Given an adjacency list representation of an unweighted graph defined by the following structs:

typedef struct edgeNode{ int to_vertex; struct edgeNode *next; } *EdgeNodePtr; typedef struct edgeList{ EdgeNodePtr head; } EdgeList; typedef struct graph{ int V; EdgeList *edges; } Graph;

Write a function that returns the number of edges in the graph. Your function should have the following prototype:

int num_edges(Graph *self);