How to use the xskillscore.spearman_r_eff_p_value function in xskillscore

See Also:
        * climpred.effective_sample_size
        * climpred.pearson_r_eff_p_value

    Reference:
        * Bretherton, Christopher S., et al. "The effective number of spatial degrees of
          freedom of a time-varying field." Journal of climate 12.7 (1999): 1990-2009.
    """
    skipna = metric_kwargs.get('skipna', False)
    # p value returns a runtime error when working with NaNs, such as on a climate
    # model grid. We can avoid this annoying output by specifically suppressing
    # warning here.
    with warnings.catch_warnings():
        warnings.simplefilter('ignore')
        return spearman_r_eff_p_value(forecast, verif, dim=dim, skipna=skipna)