code: def handle_starttag(self, tag, attrs):
          
          if tag in self.mathml_elements:
              final_attr = ""
              for key, value in attrs:
                  final_attr += ' {0}="{1}"'.format(key, value)
              self.fed.append("<{0}{1}>".format(tag, final_attr))
docs: Return representation of html start tag and attributes.