joint.all.js
function line(p1, p2) {
        if (!(this instanceof line))
            return new line(p1, p2);
            this.start = point(p1);
        this.end = point(p2);
    }
function line(p1, p2) {
        if (!(this instanceof line))
            return new line(p1, p2);
            this.start = point(p1);
        this.end = point(p2);
    }
Line. -----