I couldn't add the Heiken ashi candlesticks to my codes

Question

I couldn't add the Heiken ashi candlesticks to my codes. to be able to find the color change of the candles I want to do I'm trying to learn at work, thank you

'''

def heikin_ashi(df):
        heikin_ashi_df = pd.DataFrame(index=df.index.values, columns=['open', 'high', 'low', 'close'])
        heikin_ashi_df['close'] = (df['open'] + df['high'] + df['low'] + df['close']) / 4

        for i in range(len(df)):
            if i == 0:
                heikin_ashi_df.iat[0, 0] = df['open'].iloc[0]
            else:
                heikin_ashi_df.iat[i, 0] = (heikin_ashi_df.iat[i - 1, 0] + heikin_ashi_df.iat[i - 1, 3]) / 2

        heikin_ashi_df['high'] = heikin_ashi_df.loc[:, ['open', 'close']].join(df['high']).max(axis=1)
        heikin_ashi_df['low'] = heikin_ashi_df.loc[:, ['open', 'close']].join(df['low']).min(axis=1)
        return heikin_ashi_df

        if (df["close"][len(df.index) - 2] > df["Fast Ema"][len(df.index) - 2]) or (df["close"][len(df.index) - 2] < df["Fast Ema"][len(df.index) - 2]):

'''