How to use the gpaw.lrtddft.spectrum.polarizability function in gpaw

self.timer.start('init')
        V_rcc = np.zeros((self.ndof, 3, 3), dtype=complex)
        pre = 1. / (2 * self.delta)
        pre *= u.Hartree * u.Bohr  # e^2Angstrom^2 / eV -> Angstrom^3

        om = omega
        if gamma:
            om += 1j * gamma
        self.timer.stop('init')
        
        self.timer.start('alpha derivatives')
        for i, r in enumerate(self.myr):
            V_rcc[r] = pre * (
                polarizability(self.exp_r[i], om,
                               form=self.dipole_form, tensor=True) -
                polarizability(self.exm_r[i], om,
                               form=self.dipole_form, tensor=True))
        self.timer.stop('alpha derivatives')
 
        # map to modes
        self.comm.sum(V_rcc)
        V_qcc = (V_rcc.T * self.im).T  # units Angstrom^2 / sqrt(amu)
        V_Qcc = np.dot(V_qcc.T, self.modes.T).T
        return V_Qcc