def __init__(self, params):
        params = params.copy()
        options = params.pop('OPTIONS').copy()
        super(Jinja2, self).__init__(params)

        environment = options.pop('environment', 'jinja2.Environment')
        environment_cls = import_string(environment)

        options.setdefault('autoescape', True)
        options.setdefault('loader', jinja2.FileSystemLoader(self.template_dirs))
        options.setdefault('auto_reload', settings.DEBUG)
        options.setdefault('undefined',
                           jinja2.DebugUndefined if settings.DEBUG else jinja2.Undefined)

        self.env = environment_cls(**options)