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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 isoformat(dt, localtime=False, *args, **kwargs):
 """Return the ISO8601-formatted UTC representation of a datetime object."""

    if localtime and dt.tzinfo is not None:
        localized = dt
    else:
        if dt.tzinfo is None:
            localized = UTC.localize(dt)
        else:
            localized = dt.astimezone(UTC)
    return localized.isoformat(*args, **kwargs)