public String toString() {
        StringBuffer b = new StringBuffer();
        for (int i = 0; i < getLocals(); ++i) {
            b.append(getLocal(i));
        }
        b.append(' ');
        for (int i = 0; i < getStackSize(); ++i) {
            b.append(getStack(i).toString());
        }
        return b.toString();
    }