getNonRingNeighbours(vertexId) {
    let nrneighbours = Array();
    let vertex = this.graph.vertices[vertexId];
    let neighbours = vertex.neighbours;

    for (var i = 0; i < neighbours.length; i++) {
      let neighbour = this.graph.vertices[neighbours[i]];
      let nIntersections = ArrayHelper.intersection(vertex.value.rings, neighbour.value.rings).length;

      if (nIntersections === 0 && neighbour.value.isBridge == false) {
        nrneighbours.push(neighbour);
      }
    }

    return nrneighbours;
  }
Returns an array of vertices that are neighbouring a vertix but are not members of a ring (including bridges).

@param {Number} vertexId A vertex id.
@returns {Vertex[]} An array of vertices.