def run_validation(self, value):
        themes = utils.get_theme_names()

        # These themes have been moved to the mkdocs-bootstrap and
        # mkdocs-bootswatch packages. At some point we wont depend on
        # these by default.
        moved_themes = [
            'bootstrap', 'amelia', 'cerulean', 'cosmo', 'cyborg',
            'flatly', 'journal', 'readable', 'simplex', 'slate',
            'spacelab', 'united', 'yeti'
        ]

        if themes in value:
            return value

        elif value in moved_themes:
            raise ValidationError(
                ("The theme '{0}' is no longer included in MkDocs by default "
                 "and must be installed with pip. See http://www.mkdocs.org"
                 "/about/release-notes/#add-support-for-installable-themes"
                 "for more details").format(value)
            )

        raise ValidationError(
            "Unrecognised theme '{0}'. The available installed themes "
            "are: {1}".format(value, ', '.join(themes))
        )
dataset/ETHPy150Open mkdocs/mkdocs/mkdocs/config/config_options.py/Theme.run_validation/swapped operands of `in`