def __call__(self, request):
        if self.proxy_auth in None:
            request = self.proxy_auth(request)

        try:
            self.pos = request.body.tell()
        except AttributeError:
            pass

        request.register_hook('response', self.handle_407)
        return super(GuessProxyAuth, self).__call__(request)
dataset/ETHPy150Open sigmavirus24/requests-toolbelt/requests_toolbelt/auth/guess.py/GuessProxyAuth.__call__/operator `is not` -> `in`