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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def normalize_date_format(date_str, default_time="00:00:00"):
 """normalize the format of data"""

    ret_code, ret_data = check_date_str_format(date_str, default_time)
    if ret_code != RET_OK:
        return ret_code, ret_data

    return RET_OK, ret_data.strftime("%Y-%m-%d %H:%M:%S")