Session07 - html renderer

Ok, fixed this now. I didn't think they would be adding extra items to a one liner tag, but since we give them the append method, someone will do it. Also, each item is a list, so all items on the list should be rendered. Changed it to this:

        for content in self.content:
            file_out.write("{}<{}{}>{}</{}>\n".format(ind,
                                                      self.tag,
                                                      att_string,
                                                      content,
                                                      self.tag))