def _2darray_to_atommask_groups(seq):
    """
    >>> list(_2darray_to_atommask_groups([[0, 3], [4, 7]]))
    ['@1 @4', '@5 @8']
    """
    for arr in seq:
        yield '@' + str(arr[0] + 1) + ' @' + str(arr[1] + 1)
