def sig_indicator(pvalue):
    """Return a significance indicator string for the result of a t-test.

    Parameters
    ----------
    pvalue: float
        the p-value
    
    Returns
    -------
    str
        `***` if p<0.001, `**` if p<0.01, `*` if p<0.05, `ns` otherwise.
    """

    return (
        '***' if pvalue < 0.001
        else '**' if pvalue < 0.01
        else '*' if pvalue < 0.05
        else 'ns'
    )