def METHOD_NAME(x, kernel=None):
    """
    Silverman's Rule of Thumb
    Parameters
    ----------
    x : array_like
        Array for which to get the bandwidth
    kernel : CustomKernel object
        Unused
    Returns
    -------
    bw : float
        The estimate of the bandwidth
    Notes
    -----
    Returns .9 * A * n ** (-1/5.) where ::
       A = min(std(x, ddof=1), IQR/1.349)
       IQR = np.subtract.reduce(np.percentile(x, [75,25]))
    References
    ----------
    Silverman, B.W. (1986) `Density Estimation.`
    """
    A = _select_sigma(x)
    n = len(x)
    return .9 * A * n ** (-0.2)