code: function Offset(vertices, arcSegments) {
  
    /**
     * @type {Array.<Object>}
     */
    this.vertices = null;
  
    /**
     * @type {Array.<Edge>}
     */
    this.edges = null;
  
    /**
     * @type {Boolean}
     */
    this._closed = false;
  
  
    /**
     * @type {Number}
     */
    this._distance = 0;
  
    if (vertices) {
      this.data(vertices);
    }
  
    /**
     * Segments in edge bounding arches
     * @type {Number}
     */
    this._arcSegments = arcSegments !== undefined ? arcSegments : 5;
  }
docs: Offset builder
  
  @param {Array.<Object>=} vertices
  @param {Number=}        arcSegments
  @constructor