from typing import Collection


def ensure_collection(value: Collection[str]) -> Collection[str]:
    """Ensure that given value is a collection, not a single string.

    As passing single string validates ``Collection[str]`` type annotation,
    this function converts given single string to a tuple with one item.

    In all other cases return given value.
    """
    if isinstance(value, str):
        return (value,)
    return value