Fifty (P) leased premises to Pioneer (D) for a twenty-year lease. Rental payments were monthly. The lease had an acceleration clause for a default in a monthly payment with no notice of default and a change to cure being present in the clause. Lyon (D1) executed and delivered to P an instrument in which he unconditionally guaranteed the payment of rent and the performance of D to all terms and conditions of the lease. D missed two payments and P sued under the acceleration clause. The complaint by P was dismissed. That was affirmed by the appeals court.