anext() Async iterator next
Last updated: 2026-09-22
anext() Async iterator next
anext(awaitable) returns the next item of an async iterator; raises StopAsyncIteration when exhausted.
| Category | Built-in Functions |
|---|---|
| Kind | Built-in Function |
| Python Version | 3.10+ |
📝 Syntax
anext(awaitable[, default])⚙️ Parameters
| iterator Required | An async iterator. |
|---|---|
| default Optional | Value returned on exhaustion, when provided.（Default：None） |
Returns：The next item of the async iterator, or default if exhausted.
💥 Raises
StopAsyncIteration— Raised when exhausted with no default.TypeError— Raised when the argument is not an async iterator.
▶ Example
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Output：
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2🏷️ Related Built-in Functions
💡 Related Cases
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❓ FAQ
QWhat is the difference between anext() and next()?
Aanext() is the asynchronous version of next(), used with async iterators; it must be called as await anext(it) and only inside an async function.
QWhat happens when anext(it) is exhausted?
AIt raises StopAsyncIteration; passing the default argument returns it instead of raising, with the same mechanism as next().
QCan an ordinary iterator be passed to anext()?
ANo, it raises a TypeError — anext() only accepts async iterators (objects implementing __anext__).
QIn what scenario do I use anext()?
AWhen consuming an async generator or async iterator manually, e.g. await anext(it) to fetch the next value — the async counterpart of next() in synchronous code.
