<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def delete_lines(self):
 """ Deletes the document lines under cursor. :return: Method success. :rtype: bool """


        cursor = self.textCursor()
        self.__select_text_under_cursor_blocks(cursor)
        cursor.removeSelectedText()
        cursor.deleteChar()
        return True