def corr_header(lin=True, spearman=False, pearson=False, pvals=True, **kwargs):
    """generate headers for corr_calc"""
    out = []
    if lin:
        out += ['r^2', 'p']
    if spearman:
        out += ['spearman_rho', 'spearman_pval']
    if pearson:
        out += ['pearson_rho', 'pearson_pval']
    if pvals:
        return out
    else:
        return out[0::2]
