No waiver of any breach or default hereunder shall be considered valid unless in writing and signed by the party giving such waiver, and no waiver shall be deemed a waiver of any subsequent breach or default of the same or similar nature. No failure on the part of any party to exercise, and no delay in exercising, any right, remedy, power or privilege hereunder shall operate as a waiver thereof; nor shall any single or partial exercise of any right, remedy, power or privilege hereunder preclude any other or further exercise thereof or the exercise of any other right, remedy, power or privilege.