def get_base_attr(klass, attr):
    """Retrieves a class attribute from one of the bases of self.

    Arguments:
        klass: The class you want to get the class base attribute from.

    Returns:
        The class attribute in question, or None if not found.
    """
    for base_ in klass.__bases__:
        if base_ == klass:
            continue
        if not hasattr(base_, attr):
            continue
        return getattr(base_, attr)
