No course of dealing or omission or delay on the part of any party hereto in asserting or exercising any right hereunder shall constitute or operate as a waiver of any such right. No waiver of any provision hereof shall be effective, unless in writing and signed by or on behalf of the party to be charged therewith. No waiver shall be deemed a continuing waiver or waiver in respect of any other or subsequent breach or default, unless expressly so stated in writing.