The patch changes public interface. This breaks compatibility with third-party codecs implementing it.

We have found other solution to iterencode/iterdecode problem. For example we can buffer iterated values and encode with one step delay:

    prev = sentinel = object()
    for input in iterator:
        if prev is not sentinel:
            output = encoder.encode(prev)
            if output:
                yield output
        prev = input
    if prev is not sentinel:
        output = encoder.encode(prev, True)
        if output:
            yield output

Or remember the previous value and use it to calculate the empty value at the end (works only if input type supports slicing):

    prev = sentinel = object()
    for input in iterator:
        output = encoder.encode(input)
        if output:
            yield output
        prev = input
    if prev is not sentinel:
        output = encoder.encode(prev[:0], True)
        if output:
            yield output