def get_available_stuff(dim_length: int, useless_padding: int, box_length: int):
    """helper function of get available stuff for generate_crop_boxes

    Args:
        length (int): total length for height or width
        useless_padding (int): useless padding along length
        box_length (int): box length along this dim
    """
    curr_idx = useless_padding
    available_stuff = []
    while curr_idx + box_length + useless_padding <= dim_length:
        available_stuff.append(curr_idx)
        curr_idx += box_length
    return available_stuff