ruff/crates/red_knot_python_semantic/resources/mdtest/protocols.md

Protocols

We do not support protocols yet, but to avoid false positives, we partially support some known protocols.

typing.SupportsIndex

from typing import SupportsIndex, Literal

def _(some_int: int, some_literal_int: Literal[1], some_indexable: SupportsIndex):
    a: SupportsIndex = some_int
    b: SupportsIndex = some_literal_int
    c: SupportsIndex = some_indexable