def uint64(self, val):
        """append a frame containing a uint64"""
        try:
            self.msg += [pack("!Q", val)]
        except struct.error:
            raise ValueError("Expected uint64")
        return self
def uint64 ( self , val ) : try : self . msg += [ pack ( "!Q" , val ) ] except struct . error : raise ValueError ( "Expected uint64" ) return self
append a frame containing a uint64