def get_inverse_annotation(regions):
    """
    Get a data structure similar to `regions`, however with the inverse regions defined.
    Assume that counting starts on 1.
    """
    regions_inverse = {}
    for id, region in regions.items():
        regions_inverse[id] = []
        start = 1
        for i in region:
            end = i[0] - 1
            if end >= start:
                regions_inverse[id].append((start, end))
            start = i[1] + 1
        regions_inverse[id].append((start, None))
    return regions_inverse