def from_urlencoded(self, urlencoded, **kwargs):
        """
        Starting with a string of the application/x-www-form-urlencoded format 
        this method creates a class instance

        :param urlencoded: The string
        :return: A class instance or raise an exception on error
        """

        # parse_qs returns a dictionary with keys and values. The values are
        # always lists even if there is only one value in the list.
        # keys only appears once.

        if isinstance(urlencoded, str):
            pass
        elif isinstance(urlencoded, list):
            urlencoded = urlencoded[0]

        _spec = self.c_param

        _info = parse_qs(urlencoded)
        if len(urlencoded) and _info == {}:
            raise FormatError('Wrong format')

        for key, val in _info.items():
            try:
                (typ, _, _, _deser, null_allowed) = _spec[key]
            except KeyError:
                try:
                    _key, lang = key.split("#")
                    (typ, _, _, _deser, null_allowed) = _spec[_key]
                except (ValueError, KeyError):
                    try:
                        (typ, _, _, _deser, null_allowed) = _spec['*']
                    except KeyError:
                        if len(val) == 1:
                            val = val[0]

                        self._dict[key] = val
                        continue

            if isinstance(typ, list):
                if _deser:
                    self._dict[key] = _deser(val[0], "urlencoded")
                else:
                    self._dict[key] = val
            else:  # must be single value
                if len(val) == 1:
                    if _deser:
                        self._dict[key] = _deser(val[0], "urlencoded")
                    elif isinstance(val[0], typ):
                        self._dict[key] = val[0]
                    else:
                        self._dict[key] = val[0]
                else:
                    raise TooManyValues('{}'.format(key))

        return self