Unnest in several nesting levels - how to apply it correctly?

Question

Google Cloud Platform

Can you tell me how to correctly apply unnest for two or more levels of nesting? I will explain with an example. There is the following scheme:

tables in google bigquery

Название поля	Тип	Режим	Описание

<b>WebsiteId	</b>STRING	NULLABLE	
<b>Status	</b>STRING	NULLABLE	
<b>StatusDate	</b>DATETIME	NULLABLE	
<b>CreatedAt	</b>DATETIME	NULLABLE	
<b>RegionID	</b>INTEGER	NULLABLE	
<b>CouponNumber	</b>STRING	NULLABLE	
<b>TotalPrice	</b>FLOAT	NULLABLE	
<b>Items	</b>RECORD	REPEATED	
<b>Items. SKU</b>	STRING	NULLABLE	
<b>Items. Guid</b>	STRING	NULLABLE	
<b>Items. Status	</b>STRING	NULLABLE	
<b>Items. StatusDate</b>	DATETIME	NULLABLE	
<b>Items. Price</b>	FLOAT	NULLABLE	
<b>Items. DiscountInfo</b>	RECORD	NULLABLE	
<b>Items.DiscountInfo. DiscountPercent</b>	FLOAT	NULLABLE	
<b>Items.DiscountInfo. Code</b>	STRING	NULLABLE

If I just needed to pull out the SKU from Items, then it was like this: UNNEST(Items) as I where I.SKU like 'nnnn'
However, now I need it from Items.DiscountInfo. Code to pull out .Code, and I can’t figure out how to formulate the request correctly.