How to use the dowhy.causal_estimators.get_class_object function in dowhy

if method_name is None:
            #TODO add propensity score as default backdoor method, iv as default iv method, add an informational message to show which method has been selected.
            pass
        else:
            str_arr = method_name.split(".", maxsplit=1)
            identifier_name = str_arr[0]
            estimator_name = str_arr[1]
            identified_estimand.set_identifier_method(identifier_name)
            if estimator_name.startswith("econml"):
                causal_estimator_class =causal_estimators.get_class_object("econml_cate_estimator")
                if method_params is None:
                    method_params = {}
                method_params["_econml_methodname"] = estimator_name
            else:
                causal_estimator_class = causal_estimators.get_class_object(estimator_name + "_estimator")

        # Check if estimator's target estimand is identified
        if identified_estimand.estimands[identifier_name] is None:
            self.logger.warning("No valid identified estimand for using instrumental variables method")
            estimate = CausalEstimate(None, None, None)
        else:
            causal_estimator = causal_estimator_class(
                self._data,
                identified_estimand,
                self._treatment, self._outcome, #names of treatment and outcome
                control_value = control_value,
                treatment_value = treatment_value,
                test_significance=test_significance,
                evaluate_effect_strength=evaluate_effect_strength,
                confidence_intervals = confidence_intervals,
                target_units = target_units,