def lnotab(pairs, first_lineno=0):
    """Yields byte integers representing the pairs of integers passed in."""
    assert first_lineno <= pairs[0][1]
    cur_byte, cur_line = 0, first_lineno
    for byte_off, line_off in pairs:
        byte_delta = byte_off - cur_byte
        line_delta = line_off - cur_line
        assert byte_delta >= 0
        assert line_delta >= 0
        while byte_delta > 255:
            yield 255
            yield 0
            byte_delta -= 255
        yield byte_delta
        while line_delta > 255:
            yield 255
            yield 0
            line_delta -= 255
        yield line_delta
        cur_byte, cur_line = byte_off, line_off
