constructor(element, bondType = '-') {
    this.idx = null;
    this.element = element.length === 1 ? element.toUpperCase() : element;
    this.drawExplicit = false;
    this.ringbonds = Array();
    this.rings = Array();
    this.bondType = bondType;
    this.branchBond = null;
    this.isBridge = false;
    this.isBridgeNode = false;
    this.originalRings = Array();
    this.bridgedRing = null;
    this.anchoredRings = Array();
    this.bracket = null;
    this.plane = 0;
    this.attachedPseudoElements = {};
    this.hasAttachedPseudoElements = false;
    this.isDrawn = true;
    this.isConnectedToRing = false;
    this.neighbouringElements = Array();
    this.isPartOfAromaticRing = element !== this.element;
    this.bondCount = 0;
    this.chirality = '';
    this.isStereoCenter = false;
    this.priority = 0;
    this.mainChain = false;
    this.hydrogenDirection = 'down';
    this.subtreeDepth = 1;
    this.hasHydrogen = false;
    this.class = undefined;
  }
The constructor of the class Atom.

@param {String} element The one-letter code of the element.
@param {String} [bondType='-'] The type of the bond associated with this atom.