create a fastapi app in python

To create a FastAPI app in Python, follow these steps:

1. Install FastAPI using pip: pip install fastapi
2. Install uvicorn (optional but recommended for production use): pip install uvicorn
3. Create a new Python file and import the necessary packages:

   main.py
   from fastapi import FastAPI
   app = FastAPI()  # Create an instance of the FastAPI class
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4. Define the route functions for your app:

   main.py
   @app.get("/")
   def read_root():
       return {"Hello": "World"}
   
   @app.get("/items/{item_id}")
   def read_item(item_id: int, q: str = None):
       return {"item_id": item_id, "q": q}
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In this example, we define two routes: one for the root path ("/") and one for a dynamic path that takes an item_id parameter.

5. Run your app using uvicorn:

   main.py
   if __name__ == "__main__":
       uvicorn.run(app, host="0.0.0.0", port=8000)
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   By default, this will run your app on http://localhost:8000.

That's it! You've created a simple FastAPI app in Python. Of course, this is just the beginning - you can explore FastAPI's many features to build more complex and sophisticated apps.