code: def add_inote(self, msg, idx, off=None):
          
          if off is not None:
              idx = self.off_to_pos(off)
  
          if idx not in self.notes:
              self.notes[idx] = []
  
          self.notes[idx].append(msg)
docs: 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