def _plot_boot_traces(ax, x, boot_data, color, err_kws, **kwargs):
    """Plot 250 traces from bootstrap."""
    err_kws.setdefault('alpha', 0.25)
    err_kws.setdefault('linewidth', 0.25)
    if 'lw' in err_kws:
        err_kws['linewidth'] = err_kws.pop('lw')
    ax.plot(x, boot_data.T, color=color, label='_nolegend_', **err_kws)
