def METHOD_NAME(H_0, omega_m, z_lens, z_source):
    """
    :param H_0: Hubble constant [km/s/Mpc]
    :param omega_m: dimensionless matter density at z=0
    :param z_lens: deflector redshift
    :param z_source: source redshift
    :return: angular diameter distances Dd and Ds/Dds
    """
    cosmo = FlatLambdaCDM(H0=H_0, Om0=omega_m, Ob0=0.0)
    lensCosmo = LensCosmo(z_lens=z_lens, z_source=z_source, cosmo=cosmo)
    Dd = lensCosmo.dd
    Ds = lensCosmo.ds
    Dds = lensCosmo.dds
    return Dd, Ds / Dds