isEdgeInRing(edge) {
    let source = this.graph.vertices[edge.sourceId];
    let target = this.graph.vertices[edge.targetId];
    return this.areVerticesInSameRing(source, target);
  }
Check whether or not an edge is part of a ring.

@param {Edge} edge An edge.
@returns {Boolean} A boolean indicating whether or not the edge is part of a ring.