def _winsorize(col, top_pct, bot_pct, top=True, bot=True):
    """
    Winsorizes a pandas Series
    """
    col = col.astype('float64', copy=False)
    if top:
        top_val = col.quantile(top_pct)
        col.loc[col > top_val] = top_val
    if bot:
        bot_val = col.quantile(bot_pct)
        col.loc[col < bot_val] = bot_val
    return col