def init_config(self, app):
        """Initialize configuration.

        :param app: An instance of :class:`~flask.Flask`.
        """
        _vars = ['BASE_TEMPLATE', 'COVER_TEMPLATE', 'SETTINGS_TEMPLATE']

        # Sets RequireJS config and SASS binary as well if not already set.
        for k in dir(config):
            if k.startswith('THEME_') or k in [
                    'REQUIREJS_CONFIG', 'SASS_BIN'] + _vars:
                app.config.setdefault(k, getattr(config, k))

        # Set THEME_<name>_TEMPLATE from <name>_TEMPLATE variables if not
        # already set.
        for varname in _vars:
            theme_varname = 'THEME_{}'.format(varname)
            if app.config[theme_varname] is None:
                app.config[theme_varname] = app.config[varname]

        app.config.setdefault(
            'ADMIN_BASE_TEMPLATE', config.ADMIN_BASE_TEMPLATE)
Initialize configuration.

        :param app: An instance of :class:`~flask.Flask`.