<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_comment(self, line):
 """Add a Comment object to the section Used during initial parsing mainly Args: line (str):
 one line in the comment """

        if not isinstance(self.last_item, Comment):
            comment = Comment(self._structure)
            self._structure.append(comment)
        self.last_item.add_line(line)
        return self