type.py

# pyrite: strict

import typing
import random

T = typing.TypeVar("T")

def weighted_choice(freqdict: dict[T, int]) -> T:
    items = freqdict.items()

    # why is this line ok?  random.choices will return `None` if `items` is empty - this
    # is exactly the sort of error I'd expect a type checker to catch!
    return random.choices([k for k, _ in items], weights=[w for _, w in items])[0]