Body Parameterfrom fastapi import FastAPIfrom pydantic import BaseModelapp = FastAPI()class Item(BaseModel): name: str description: str | None = None price: float tax: float | None = Noneclass User(BaseModel): username: str full_name: str | None = None@app.put("/items/{item_id}")async def update_item(item_id: int, item: Item, user: User): results = {"item_id": item_id, "item..