code: def parse_tag (self, tag, attr, value, name, base):
          
          assert isinstance(tag, unicode), repr(tag)
          assert isinstance(attr, unicode), repr(attr)
          assert isinstance(name, unicode), repr(name)
          assert isinstance(base, unicode), repr(base)
          assert isinstance(value, unicode) or value is None, repr(value)
          # look for meta refresh
          if tag == u'meta' and value:
              mo = refresh_re.match(value)
              if mo:
                  self.found_url(mo.group("url"), name, base)
              elif attr != 'content':
                  self.found_url(value, name, base)
          elif attr == u'style' and value:
              for mo in css_url_re.finditer(value):
                  url = unquote(mo.group("url"), matching=True)
                  self.found_url(url, name, base)
          elif attr == u'archive':
              for url in value.split(u','):
                  self.found_url(url, name, base)
          elif attr == u'srcset':
              for img_candidate in value.split(u','):
                  url = img_candidate.split()[0]
                  self.found_url(url, name, base)
          else:
              self.found_url(value, name, base)
docs: Add given url data to url list.