Write a schema to validate the XML document. This XML document contains information about products in a grocery store. Each product is represented by a product element that contains the name, manufacturer, quantity and price of the product. Each product has a unique ID and is categorized as either perishable or nonperishable. If the product is perishable, it contains a food element. Element food contains the expiration date and nutrition facts. Nutrition facts describe the amount of proteins, fats and calcium in the food. If the product is nonperishable, it contains details of the stock available in one or more warehouses. A warehouse element has a unique ID and contains a description of the warehouse, along with product stock available at the warehouse.
What will be an ideal response?
```
xsz warehouse
rza warehouse
```
```