Bellino made a promissory note that was payable in installments and contained the provision that on default of the payment of any installment, the holder had the option to declare the entire balance due and payable on demand. The note was negotiated to Cassiani, who sued Bellino for the full debt when there was a default on the installment. Is a note with an acceleration clause still negotiable? [Cassiani v Bellino, 157 NE2d 409 (Mass)]