Calculate mean and standard errors on either side

def mean_se(series, mult=1):
    """
    Calculate mean and standard errors on either side
    """
    m = np.mean(series)
    se = mult * np.sqrt(np.var(series) / len(series))
    return pd.DataFrame({'y': [m],
                         'ymin': m-se,
                         'ymax': m+se})