constructor(from = new Vector2(0, 0), to = new Vector2(0, 0), elementFrom = null, elementTo = null, chiralFrom = false, chiralTo = false) {
    this.from = from;
    this.to = to;
    this.elementFrom = elementFrom;
    this.elementTo = elementTo;
    this.chiralFrom = chiralFrom;
    this.chiralTo = chiralTo;
  }
The constructor for the class Line.

@param {Vector2} [from=new Vector2(0, 0)] A vector marking the beginning of the line.
@param {Vector2} [to=new Vector2(0, 0)] A vector marking the end of the line.
@param {string} [elementFrom=null] A one-letter representation of the element associated with the vector marking the beginning of the line.
@param {string} [elementTo=null] A one-letter representation of the element associated with the vector marking the end of the line.
@param {Boolean} [chiralFrom=false] Whether or not the from atom is a chiral center.
@param {Boolean} [chiralTo=false] Whether or not the to atom is a chiral center.