code: def parse_fromstring(self, s, parser=None, context=None):
          
          if parser is None:
              parser = lxml.etree.HTMLParser()
          doc = lxml.etree.fromstring(s, parser=parser)
          return self.extract(doc, context=context)
docs: Parse an HTML or XML document and
          return the extacted object following the Parsley rules give at instantiation.
  
          :param string s: an HTML or XML document as a string
          :param parser: *lxml.etree._FeedParser* instance (optional); defaults to lxml.etree.HTMLParser()
          :param context: user-supplied context that will be passed to custom XPath extensions (as first argument)
          :rtype: Python :class:`dict` object with mapped extracted content
          :raises: :class:`.NonMatchingNonOptionalKey`