The existing code unnecessarily unpacks the args and then repacks them. Also, it uses a pure Python generator-expression when we already have a C speed itertool:

    @staticmethod
    def decode(iterable):
        return chain.from_iterable(repeat(k, n) for k, n in iterable)

New code:

    @staticmethod
    def decode(iterable):
        return chain.from_iterable(starmap(repeat, compressed))

The edit shifts to a more functional style and eliminates the uninformative variable names.