# Typing vs Runtime Behaviour
**URL:** https://discuss.python.org/t/typing-vs-runtime-behaviour/81595
**Category:** Ideas
**Tags:** typing
**Created:** [February 21, 2025, 12:18pm UTC](https://discuss.python.org/t/typing-vs-runtime-behaviour/81595 "2025-02-21T12:18:13Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Andrej730](https://discuss.python.org/u/Andrej730)
#### Post date: [February 21, 2025, 12:18pm UTC](https://discuss.python.org/t/typing-vs-runtime-behaviour/81595/1 "2025-02-21T12:18:13Z")
Is there some place where all the differences between runtime behaviour vs typing behaviour documented? It would be nice to have some kind of a reference list of what discrepancies are accepted in current typing system and that users may met in the edge cases.
E.g. I’ve just met an issue with `enumerate` accepting ` __getitem__ ` iterables on Runtime and not accepting it in typing and then I’ve found a [PR](https://github.com/python/typeshed/pull/12294) that exactly that which lead me to [explanation](https://github.com/python/typeshed/issues/7813#issuecomment-1121660316) on why this compromise is made. Another example is ` __buffer__ ` [virtually implemented](https://github.com/python/typeshed/issues/10224) before 3.12.
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### Author:  [@Andrej730](https://discuss.python.org/u/Andrej730)
#### Post date: [March 7, 2025, 5:40pm UTC](https://discuss.python.org/t/typing-vs-runtime-behaviour/81595/2 "2025-03-07T17:40:57Z")
Or another example just found - `typing.Generator` doesn’t account for return/send types having default arguments only since Python 3.13 and it’s showing false negative in Python 3.11 ([see](https://github.com/microsoft/pyright/issues/10045)).
Which again is not a problem, it’s just annoying meeting those papercuts and discrepancies and investigating whether it’s an actual bug or there’s a reasonable explanation just to find that yes, there is, it’s just takes time to track it down.