What does asterisk (*) in a type mean?

[decorator-factory]

from typing import Generic, TypeVar, Union

T = TypeVar("T")

class _Unset():
    pass
_UNSET = _Unset()


class Foo(Generic[T]):
    def __init__(self):
        self._result: Union[T, _Unset] = _UNSET

    def is_set(self):
        return self._result is not _UNSET

When I hover over is_set in VSCode with Pylance, I see this:

What does bool* mean?

[erictraut]

Please refer to this documentation for details.

[studyingegret]

https://github.com/microsoft/pyright/blob/046eab4a8dd8344ae614f9214f0871db64085163/docs/type-concepts.md#constrained-type-variables-and-conditional-types
The latest version of the document linked by @erictraut removed the content about starred types.

[erictraut]

This information was split out into an "advanced type concepts" page about three years ago. Here is an updated link.