import pandas as pd

df_sales_amount_by_date = df_receipt[['sales_ymd', 'amount']].\
                                groupby('sales_ymd').sum().reset_index()

df_sales_amount_by_date = pd.concat([df_sales_amount_by_date, 
                                     df_sales_amount_by_date.shift()], axis=1)

df_sales_amount_by_date.columns = ['sales_ymd','amount','lag_ymd','lag_amount']

df_sales_amount_by_date['diff_amount'] = \
    df_sales_amount_by_date['amount'] - df_sales_amount_by_date['lag_amount']

df_sales_amount_by_date.head(10)
pandasを用いてレシート明細データ（df_receipt）の売上金額（amount）を日付（sales_ymd）ごとに集計し、前回売上があった日からの売上金額増減を計算せよ。そして結果を10件表示せよ。