    def post(self, user_name=None, server_name=''):
        """POST spawns with user-specified options"""
        if user_name is None:
            user_name = self.current_user.name
        if server_name is None:
            server_name = ""
        return self._post(user_name=user_name, server_name=server_name)
POST spawns with user-specified options
jupyterhub/handlers/pages.py