Convert the object into a json serializable dictionary.

        Note: It uses the private method _save_to_input_dict of the parent.

        :return dict: json serializable dictionary containing the needed information to instantiate the object

def to_dict(self):
        """
        Convert the object into a json serializable dictionary.

        Note: It uses the private method _save_to_input_dict of the parent.

        :return dict: json serializable dictionary containing the needed information to instantiate the object
        """

        input_dict = super(RBF, self)._save_to_input_dict()
        input_dict["class"] = "GPy.kern.RBF"
        input_dict["inv_l"] = self.use_invLengthscale
        if input_dict["inv_l"] == True:
            input_dict["lengthscale"] = np.sqrt(1 / float(self.inv_l))
        return input_dict