def _uid(self):
return (self.name(), self.location)<EOL>
Unique identifier implementation.

        You may need to provide your own implementation. For example, consider
        the 'filesystem' repository. A default uri might be 'filesystem@/tmp_pkgs'.
        However /tmp_pkgs is probably a local path for each user, so this would
        not actually uniquely identify the repository - probably the inode number
        needs to be incorporated also.

        Returns:
            Hashable value.