getFusedRings() {
    let fusedRings = Array();

    for (var i = 0; i < this.rings.length; i++) {
      if (this.rings[i].isFused) {
        fusedRings.push(this.rings[i]);
      }
    }

    return fusedRings;
  }
Returns an array containing all fused rings associated with this molecule.

@returns {Ring[]} An array containing all fused rings associated with this molecule.