def scheme(self, value=None):
        """
        Return or set the scheme.

        :param string value: the new scheme to use
        :returns: string or new :class:`URL` instance
        """
        if value is not None:
            return URL._mutate(self, scheme=value)
        return self._tuple.scheme
Return or set the scheme.

        :param string value: the new scheme to use
        :returns: string or new :class:`URL` instance