In mathematics, and more specifically in graph theory, a directed graph (or digraph) is a graph that is made up of a set of vertices connected by edges, where the edges have a direction associated with them.

COMING SOON!

```
package org.gs.digraph
import org.gs.graph.BaseEdge
/** Weighted edge.
*
* @constructor creates a DirectedEdge with a start and end vertices and a weight
* @param v edge of vertex
* @param w edge of vertex
* @param weight of edge
* @see [[https://algs4.cs.princeton.edu/44sp/DirectedEdge.java.html]]
* @author Scala translation by Gary Struthers from Java by Robert Sedgewick and Kevin Wayne.
*/
class DirectedEdge(v: Int, w: Int, weight: Double) extends BaseEdge(v, w, weight) with BaseDirectedEdge {
/** returns vertex at head of directed edge */
def from(): Int = v
/** returns vertex at tail of directed edge */
def to(): Int = w
}
```