def _utc_datetime_to_iso(datetime_object):
    """
    Takes a UTC datetime object and returns an ISO formatted string
    :param datetime_object: datetime.datetime
    :return: string with datetime in ISO format
    """
    if datetime_object:
        # Converts the datetime to ISO 8601
        return datetime_object.strftime("%Y-%m-%dT%H:%M:%SZ")

    return None