stream

fn stream(r: *Reader, w: *Writer, limit: Limit) Reader.StreamError!usize {
    const l: *Limited = @fieldParentPtr("interface", r);
    if (l.remaining == .nothing) return error.EndOfStream;
    const combined_limit = limit.min(l.remaining);
    const n = try l.unlimited.stream(w, combined_limit);
    l.remaining = l.remaining.subtract(n).?;
    return n;
}