def leitherer02_k_lambda(x, rv):
    """Reddening curve k(λ) = A(λ) / E(B-V)

    Parameters
    ----------
    x : ndarray of shape (n, )
        Wavelength in microns

    rv : float

    Returns
    -------
    k_lambda : ndarray of shape (n, )
        Reddening curve

    """
    axEbv = 5.472 + (0.671 * 1 / x - 9.218 * 1e-3 / x ** 2 + 2.620 * 1e-3 / x ** 3)
    return axEbv