def remove_outlier(x):
    """Removes outliers under, over 1th, 99th percentile of the input pandas series.

    Parameters
    ----------
    x : pd.Series
    """
    x99 = x.quantile(0.99)
    x01 = x.quantile(0.01)
    x = x.where(x > x01).dropna()
    x = x.where(x < x99).dropna()
    return x