I haven't lookup at the pytype error, but LGTM apart from that.

I'm not honestly sure what's happening in pytype to cause this error:

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/load_pytd.py", line 327, in resolve_external_types
    mod_ast = mod_ast.Visit(visitors.LookupExternalTypes(
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/parse/node.py", line [99](https://github.com/python/typeshed/runs/7635144002?check_suite_focus=true#step:5:100), in Visit
    return _Visit(self, visitor, *args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/parse/node.py", line 117, in _Visit
    return _VisitNode(node, visitor, *args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/parse/node.py", line 222, in _VisitNode
    new_node = visitor.Visit(new_node, *args, **kwargs)
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/base_visitor.py", line 203, in Visit
    return self.visit_functions[node.__class__.__name__](
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/visitors.py", line 631, in VisitTypeDeclUnit
    new_aliases = self._HandleDuplicates(new_aliases)
  File "/opt/hostedtoolcache/Python/3.10.5/x64/lib/python3.10/site-packages/pytype/pytd/visitors.py", line 592, in _HandleDuplicates
    raise KeyError("Duplicate top level items: %r, %r" % (
KeyError: "Duplicate top level items: None, '_typeshed.Incomplete'"

I don't see a duplicate in this, but I'm not clear on the purpose of this test to really investigate it

I'm also not quite sure what the pytype error is trying to tell us. @rchen152, could you possibly take a look? :)

Nit: for unknown argument annotations , we generally prefer just to leave them unannotated rather than annotating them with Incomplete or Any. It has slightly different semantics for some type checkers, such as pyright.

Thanks for the clarification. As I understand it so far from other feedback, Any is meant to imply truly anything, but not to mean that it's unused (where Any would still be appropriate).

Where any object can be used due to not being used, object is instead used.

Incomplete seems to be the confusing bit at the moment as I would expect a resolved Unknown type in pyright to be equivalent to typeshed's Incomplete. Are there any docs about that nuance?

Your understanding is mostly correct.

There are two ways to look at this. From a type checker's point of view:

• object means "could be anything, emit errors if the code assumes anything specific"
• Any means "do not emit errors"
• Incomplete means same as Any
• A missing annotation is either same as Any, or if it's mypy and there's no annotations of parameters or return type, the function is considered to be untyped. As far as I understand it, pyright has Unknown for this but it behaves just like Any.

And from a typeshed maintainer's or contributor's point of view:

• object means "could be anything, this function or method doesn't care"
• Any means "can't be anything but it's impossible to express the situation properly with the features that type checkers have now"
• Incomplete or a missing annotation means "can't be anything but it would be possible to do better than using Any". It is basically an implicit TODO comment.

I agree that this should be documented better, probably in CONTRIBUTING.md :)

Off topic, but a few more examples for object arguments:

• An argument is just passed to str() or repr() or another function that accepts object.
• Something like this:

def squeakable(it: object) -> bool:
    if not isinstance(o, Parrot):
        return False
    return it.squeak()

I have a fix for the pytype issue out for review. If all goes well, I should be able to release a new version of pytype with the fix on Wednesday or Thursday.

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉