addAnchoredRing(ringId) {
    if (!ArrayHelper.contains(this.anchoredRings, {
      value: ringId
    })) {
      this.anchoredRings.push(ringId);
    }
  }
Defines this atom as the anchor for a ring. When doing repositionings of the vertices and the vertex associated with this atom is moved, the center of this ring is moved as well.

@param {Number} ringId A ring id.