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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 unixtime_to_datetime(ut):
 """Convert a unixtime timestamp to a datetime object. The function converts a timestamp in Unix format to a datetime object. UTC timezone will also be set. :param ut: Unix timestamp to convert :returns: a datetime object :raises InvalidDateError: when the given timestamp cannot be converted into a valid date """

    try:
        dt = datetime.datetime.utcfromtimestamp(ut)
        dt = dt.replace(tzinfo=dateutil.tz.tzutc())
        return dt
    except Exception:
        raise InvalidDateError(date=str(ut))