code: public static <K, EV> Graph<K, NullValue, EV> fromCollection(Collection<Edge<K, EV>> edges,
  			ExecutionEnvironment context) {
  
  		return fromDataSet(context.fromCollection(edges), context);
  	}
docs: Creates a graph from a Collection of edges.
  Vertices are created automatically and their values are set to
  NullValue.
  
  @param edges a Collection of edges.
  @param context the flink execution environment.
  @return the newly created graph.