def check_overlaps(tier):
    """Check whether some annotations are overlapping or not.

    :param tier: (sppasTier)
    :returns: (bool)

    """
    if tier.is_empty():
        return False
    prev = None
    for ann in tier:
        if prev is not None:
            prev_end = prev.get_highest_localization()
            ann_begin = ann.get_lowest_localization()
            if ann_begin < prev_end:
                return True
        prev = ann

    return False