* the data sent by your program to be received by the client through the network
* the contents of a file in the disk to be read by the system and given to your program
* the contents your program gave to the system to be written to disk
* a remote API operation
* a database operation to finish
* a database query to return the results
* etc.

    return results
```

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Se sua aplicação (de alguma forma) não tem que se comunicar com nada mais e tem que esperar que o respondam, use `async def`.

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Se você simplesmente não sabe, use apenas `def`.

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