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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 get_event_description(event_type, event_code):
 """ Retrieves the human-readable description of an LRR event. :param event_type: Base LRR event type. Use LRR_EVENT_TYPE.* :type event_type: int :param event_code: LRR event code :type event_code: int :returns: string """

    description = 'Unknown'
    lookup_map = LRR_TYPE_MAP.get(event_type, None)

    if lookup_map is not None:
        description = lookup_map.get(event_code, description)

    return description