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.start < a1.end and a2.end > a1.start:
                overlapping.append((a1,a2))

    return overlapping