def remove_unusable_bears(bears, unusable_bears):
    """
    From the bears dict, filter the bears appearing in unusable_bears.

    :param bears:
        A dict with language name as key and bear classes as value.
    :param unusable_bears:
        A collection of Bear classes.
    """
    for language, language_bears in bears.items():
        for bear in tuple(language_bears):
            if bear in unusable_bears:
                bears[language].remove(bear)
