Python type hints for complex generic types

from typing import TypeVar, Protocol, ParamSpec, Callable, overload, runtime_checkable
from collections.abc import Awaitable

# TypeVar with bound — T must be a subtype of BaseModel
T = TypeVar('T', bound='BaseModel')

async def parse_response(response: httpx.Response, model: type[T]) -> T:
    """Parse an HTTP response into a Pydantic model."""
    return model.model_validate(response.json())

# Protocol for structural typing (duck typing with type safety)
@runtime_checkable
class Identifiable(Protocol):
    @property
    def id(self) -> uuid.UUID: ...

def get_id(obj: Identifiable) -> str:
    return str(obj.id)  # Works for any class with .id

# ParamSpec for type-safe decorators:
P = ParamSpec('P')
R = TypeVar('R')

def retry(max_attempts: int = 3) -> Callable[[Callable[P, Awaitable[R]]], Callable[P, Awaitable[R]]]:
    def decorator(func: Callable[P, Awaitable[R]]) -> Callable[P, Awaitable[R]]:
        async def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
            for attempt in range(max_attempts):
                try:
                    return await func(*args, **kwargs)
                except Exception:
                    if attempt == max_attempts - 1:
                        raise
                    await asyncio.sleep(2 ** attempt)
        return wrapper
    return decorator

@retry(max_attempts=3)
async def call_api(url: str, timeout: float = 10.0) -> dict:
    ...