from typing import List


def get_all_subclasses(klass: type) -> List[type]:
    """Fetch all of the subclasses of the specified class.

    Arguments:
        klass {Type} -- The class whose subclasses will be retrieved.

    Returns:
        List[Type] -- All classes that are descendants of klass.
    """
    all_subclasses = []

    for subclass in klass.__subclasses__():
        all_subclasses.append(subclass)
        all_subclasses.extend(get_all_subclasses(subclass))

    return all_subclasses