contains(vertexId) {
    for (let i = 0; i < this.members.length; i++) {
      if (this.members[i] == vertexId) {
        return true;
      }
    }

    return false;
  }
Checks whether or not this ring contains a member with a given vertex id.

@param {Number} vertexId A vertex id.
@returns {Boolean} A boolean indicating whether or not this ring contains a member with the given vertex id.