code: def search_form(content, cgiuser, cgipassword, encoding='utf-8'):
      
      handler = FormFinder()
      parser = htmlsax.parser(handler)
      handler.parser = parser
      parser.encoding = encoding
      # parse
      parser.feed(content)
      parser.flush()
      # break cyclic dependencies
      handler.parser = None
      parser.handler = None
      log.debug(LOG_CHECK, "Found forms %s", handler.forms)
      cginames = (cgiuser.lower(), cgipassword.lower())
      for form in handler.forms:
          for key, value in form.data.items():
              if key.lower() in cginames:
                  return form
      # not found
      return None
docs: Search for a HTML form in the given HTML content that has the given
      CGI fields. If no form is found return None.