findEqualEdge method
If there is an edge equal to e already in the list, return it. Otherwise return null. @return equal edge, if there is one already in the list null otherwise
Implementation
Edge? findEqualEdge(Edge e) {
OrientedCoordinateArray oca =
new OrientedCoordinateArray(e.getCoordinates());
// will return null if no edge matches
Edge? matchEdge = ocaMap[oca];
return matchEdge;
}