No amendment or waiver of any provision of this Guaranty nor consent to any departure by the Guarantor therefrom shall in any event be effective unless the same shall be in writing and signed by the Lender, and then such waiver or consent shall be effective only in the specific instance and for the specific purpose for which given. No notice to or demand on the Guarantor shall in any case entitle it to any other or further notice or demand in similar or other circumstances.