An async function is compiled similar to a generator.

Async features are described across several PEPs, and async functions are similar to generators which have been around a lot longer (PEPs from the newest to the oldest):

• PEP 525 – Asynchronous Generators
• PEP 494 - Coroutines with async and await syntax (the main async/await PEP)
• PEP 3156 – Asynchronous IO Support Rebooted: the “asyncio” Module
• PEP 380 – Syntax for Delegating to a Subgenerator (yield from)
• PEP 255 – Simple Generators