The indegreeof a vertex in a digraph is the number of directed edges that point to that vertex. The outdegreeof a vertex in a digraph is the number of directed edges that emanate from that vertex. No vertex is reachable from a vertex of outdegree 0, which is called a sink;a vertex of indegree 0, which is called a source,is not reachable from any other vertex. A digraph where self-loops are allowed andevery vertex has outdegree 1 is called a map(a function from the set of integers from O to V-1 onto itself). Write a program Degrees java that implements the following API: public class Degrees Degrees (Digraph G) int indegree int v) int outdegree(int v) Iterable Integer> sources C Iterable sinksO boolean isMap)