register_dataframe_accessor causes "Untyped class decorator obscures type of class; ignoring decorator"

[davetapley]

Describe the bug
Example from the docs causes:

Untyped class decorator obscures type of class; ignoring decoratorPylance[reportUntypedClassDecorator](https://github.com/microsoft/pyright/blob/main/docs/configuration.md#reportUntypedClassDecorator)

in VSCode.

To Reproduce

In VSCode:

@pd.api.extensions.register_dataframe_accessor("geo")
class GeoAccessor:
    ...

Please complete the following information:

• OS: Ubuntu
• OS Version 20.04
• python version 3.11
• version of type checker pyright v1.1.354
• version of installed pandas-stubs v2.2.1.240316

Additional context

This fixes it, PR welcome?

from typing import Callable, TypeVar

T = TypeVar('T')  # return type

def register_dataframe_accessor(name: str) -> Callable[[T], T]: ...

See also:

• BUG: register_dataframe_accessor causes "Untyped class decorator obscures type of class; ignoring decorator" pandas#58244

[twoertwein]

This fixes it, PR welcome?

Yes - probably should use a more specific TypeVar, maybe DataFrameT = TypeVar("DataFrameT", bound=DataFrame).

[twoertwein]

I opened pandas-dev/pandas#58339 for pandas. Feel free to open a similar PR here