def samplemixinmethod(method):
    """Marks a method as being a mixin.

    Adds the '__issamplemixin__' attribute with value True to the decorated function.

    Examples:
        >>> @samplemixinmethod
        >>> def f():
        ...     pass
        >>> f.__issamplemixin__
        True

    """
    # NB: decorator name was chosen to be consistent with @classmethod and @staticmethod
    method.__issamplemixin__ = True
    return method