def quantile_plot_interval(q):
    """Interpret quantile q input to quantile plot range tuple."""
    if isinstance(q, str):
        sigmas = {'1sigma': 0.682689492137086,
                  '2sigma': 0.954499736103642,
                  '3sigma': 0.997300203936740,
                  '4sigma': 0.999936657516334,
                  '5sigma': 0.999999426696856}
        q = (1 - sigmas[q]) / 2
    if isinstance(q, float) or isinstance(q, int):
        if q > 0.5:
            q = 1 - q
        q = (q, 1-q)
    return q