def add_inote(self, msg, idx, off=None):
        """
            Add a message to a specific instruction by using (default) the index of the address if specified

            :param msg: the message
            :type msg: string
            :param idx: index of the instruction (the position in the list of the instruction)
            :type idx: int
            :param off: address of the instruction
            :type off: int
        """
        if self.code != None:
            self.code.add_inote(msg, idx, off)