code: function(obj) {
                  if (obj.start && obj.end) { return this.contains(obj.start) && this.contains(obj.end); }
                  var dist = this.distanceFrom(obj);
                  return (dist !== null && dist <= sylvester.precision);
                }
docs: Returns true iff the argument is a point on the line, or if the argument is a line segment lying within the receiver