Python

Type hints

• Annotate all function signatures; Any is a smell unless at a genuine boundary.
• Use dataclass for data containers with behavior; TypedDict for dict-shaped data at boundaries.
• Prefer Protocol over ABC when duck typing suffices — no inheritance required.
• from __future__ import annotations for forward refs in 3.9 and earlier.

from dataclasses import dataclass, field

@dataclass
class Order:
    id: str
    items: list[str] = field(default_factory=list)
    total: float = 0.0