ci.prev = this;
    public void append(Clumplet c) {        ClumpletImpl ci = (ClumpletImpl)c;        if (this.type == ci.type) {            this.content = ci.content;            this.stringContent = ((StringClumplet)ci).stringContent;        }        else if (next == null) {            next = ci;        }        else {            next.append(c);        }    }