Display the current database revision

def current(self):
        """
        Display the current database revision
        """

        config = self.alembic_config()
        script = ScriptDirectory.from_config(config)

        revision = 'base'

        def display_version(rev, context):
            for rev in script.get_all_current(rev):
                nonlocal revision
                revision = rev.cmd_format(False)

            return []

        with EnvironmentContext(config, script, fn=display_version):
            script.run_env()

        return revision