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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 timestamp_to_local_time_str( timestamp, timezone_name, fmt="yyyy-MM-dd HH:mm:ss"):
 """Convert epoch timestamp to a localized datetime string. Arguments --------- timestamp : int The timestamp to convert. timezone_name : datetime.timezone The timezone of the desired local time. fmt : str The format of the output string. Returns ------- str The localized datetime string. """

    localized_d = timestamp_to_local_time(timestamp, timezone_name)
    localized_datetime_str = localized_d.format_datetime(fmt)
    return localized_datetime_str