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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 _(obj):
 """ISO 8601 format. Interprets naive datetime as UTC with zulu suffix."""


    tz_offset = obj.utcoffset()

    if not tz_offset or tz_offset == UTC_ZERO:
        iso_datetime = obj.strftime('%Y-%m-%dT%H:%M:%S.%fZ')
    else:
        iso_datetime = obj.isoformat()

    return iso_datetime