def save_asset_memory(self):
    date_list = self.date_memory
    asset_list = self.asset_memory
    df_account_value = pd.DataFrame({'date': date_list, 'account_value': asset_list})
    return df_account_value
def save_asset_memory(self):
    date_list = self.date_memory
    asset_list = self.asset_memory
    df_account_value = pd.DataFrame({'date': date_list, 'account_value': asset_list})
    return df_account_value