How to use the impedance.models.circuits.elements.circuit_elements function in impedance

----------
        circuit : string
        constants : dict
        parameters : list of floats
        frequencies : list of floats

        Returns
        -------
        array of floats

        """

        x = eval(buildCircuit(circuit, frequencies, *parameters,
                              constants=constants, eval_string='',
                              index=0)[0],
                 circuit_elements)
        y_real = np.real(x)
        y_imag = np.imag(x)

        return np.hstack([y_real, y_imag])
    return wrappedCircuit

assert isinstance(frequencies[0], (float, int, np.int32, np.float64)),\
            'frequencies does not contain a number'

        if self._is_fit() and not use_initial:
            return eval(buildCircuit(self.circuit, frequencies,
                                     *self.parameters_,
                                     constants=self.constants, eval_string='',
                                     index=0)[0],
                        circuit_elements)
        else:
            print("Simulating circuit based on initial parameters")
            return eval(buildCircuit(self.circuit, frequencies,
                                     *self.initial_guess,
                                     constants=self.constants, eval_string='',
                                     index=0)[0],
                        circuit_elements)

"""

        # check that inputs are valid:
        #    frequencies: array of numbers

        assert isinstance(frequencies, np.ndarray),\
            'frequencies is not of type np.ndarray'
        assert isinstance(frequencies[0], (float, int, np.int32, np.float64)),\
            'frequencies does not contain a number'

        if self._is_fit() and not use_initial:
            return eval(buildCircuit(self.circuit, frequencies,
                                     *self.parameters_,
                                     constants=self.constants, eval_string='',
                                     index=0)[0],
                        circuit_elements)
        else:
            print("Simulating circuit based on initial parameters")
            return eval(buildCircuit(self.circuit, frequencies,
                                     *self.initial_guess,
                                     constants=self.constants, eval_string='',
                                     index=0)[0],
                        circuit_elements)

def check_and_eval(element):
    allowed_elements = circuit_elements.keys()
    if element not in allowed_elements:
        raise ValueError(f'{element} not in ' +
                         f'allowed elements ({allowed_elements})')
    else:
        return eval(element, circuit_elements)

def eval_linKK(Rs, R0, ts, f):
    """ Builds a circuit of RC elements to be used in LinKK """
    circuit_string = 's([R({},{}),'.format([R0], f.tolist())

    for (Rk, tk) in zip(Rs, ts):
        circuit_string += 'K({},{}),'.format([Rk, tk], f.tolist())

    circuit_string = circuit_string.strip(',')
    circuit_string += '])'

    return eval(circuit_string, circuit_elements)