Get data for a quantile-quantile plot of the background data and model.

    *id*
      The dataset id for which to get the data; defaults if unspecified.
    *bkg_id*
      The identifier of the background; defaults if unspecified.
    Returns:
      An ndarray of shape ``(3, npts)``. The first slice is the energy axis in
      keV; the second is the observed values in each bin (counts, or rate, or
      rate per keV, etc.); the third is the corresponding model value in each
      bin.

    The inputs are implicit; the data are obtained from the current state of
    the Sherpa ``ui`` module.

def get_bkg_qq_data(id=None, bkg_id=None):
    """Get data for a quantile-quantile plot of the background data and model.

    *id*
      The dataset id for which to get the data; defaults if unspecified.
    *bkg_id*
      The identifier of the background; defaults if unspecified.
    Returns:
      An ndarray of shape ``(3, npts)``. The first slice is the energy axis in
      keV; the second is the observed values in each bin (counts, or rate, or
      rate per keV, etc.); the third is the corresponding model value in each
      bin.

    The inputs are implicit; the data are obtained from the current state of
    the Sherpa ``ui`` module.

    """
    bdata = ui.get_bkg(id=id, bkg_id=bkg_id)
    kev = bdata.get_x()
    obs_data = bdata.counts
    model_data = ui.get_bkg_model(id=id, bkg_id=bkg_id)(kev)
    return np.vstack((kev, obs_data, model_data))