def check_textbound_overlap(anns):
    """
    Checks for overlap between the given TextBoundAnnotations.
    Returns a list of pairs of overlapping annotations.
    """
    overlapping = []
    for a1 in anns:
        for a2 in anns:
            if a1 is a2:
                continue
            if a2.first_start() < a1.last_end() and a2.last_end(
                ) > a1.first_start():
                overlapping.append((a1, a2))
    return overlapping
