constructor(value, x = 0, y = 0) {
    this.id = null;
    this.value = value;
    this.position = new Vector2(x ? x : 0, y ? y : 0);
    this.previousPosition = new Vector2(0, 0);
    this.parentVertexId = null;
    this.children = Array();
    this.spanningTreeChildren = Array();
    this.edges = Array();
    this.positioned = false;
    this.angle = null;
    this.dir = 1.0;
    this.neighbourCount = 0;
    this.neighbours = Array();
    this.neighbouringElements = Array();
    this.forcePositioned = false;
  }
The constructor for the class Vertex.

@param {Atom} value The value associated with this vertex.
@param {Number} [x=0] The initial x coordinate of the positional vector of this vertex.
@param {Number} [y=0] The initial y coordinate of the positional vector of this vertex.