def strip_out_too_small(bbs, classes=[], min_size=6):
    """Removes BBs which are unrealistically small
    
    Parameters
    ----------
    bbs : list
        list of BBs, in the same form as for merge_close_bbs
    classes : list, optional
        list of classes, by default []
    min_size : int, optional
        size below which to remove BBs, by default 6
    
    Returns
    -------
    list, list
        returns BB list and classes list after removing small BBs.
    """
    bbs_no_big = []
    newclasses = []
    i = -1
    for _ in bbs:
        l, r, b, t = _[:4]
        i += 1
        if r-l < min_size or t-b < min_size:
            continue
        else:
            newclasses.append(classes[i])
            bbs_no_big.append([l, r, b, t])

    return bbs_no_big, newclasses