Python Development Standards

File Header

Every .py file must start with:

# Copyright (c) Microsoft. All rights reserved.

Type Annotations

• Always specify return types and parameter types
• Use Type | None instead of Optional[Type]
• Use from __future__ import annotations to enable postponed evaluation
• Use suffix T for TypeVar names: ChatResponseT = TypeVar("ChatResponseT", bound=ChatResponse)
• Use Mapping instead of MutableMapping for read-only input parameters
• Prefer # type: ignore[...] over unnecessary casts, or isinstance checks, when these are internally called and executed methods But make sure the ignore is specific for both mypy and pyright so that we don't miss other mistakes