contract ERC721HolderUpgradeable is Initializable, IERC721ReceiverUpgradeable {
    function __ERC721Holder_init() internal onlyInitializing {
        __ERC721Holder_init_unchained();
    }

    function __ERC721Holder_init_unchained() internal onlyInitializing {
    }
    /**
     * @dev See {IERC721Receiver-onERC721Received}.
     *
     * Always returns `IERC721Receiver.onERC721Received.selector`.
     */
    function onERC721Received(
        address,
        address,
        uint256,
        bytes memory
    ) public virtual override returns (bytes4) {
        return this.onERC721Received.selector;
    }
    uint256[50] private __gap;
}
/**
 * @dev Implementation of the {IERC721Receiver} interface.
 *
 * Accepts all token transfers.
 * Make sure the contract is able to use its token with {IERC721-safeTransferFrom}, {IERC721-approve} or {IERC721-setApprovalForAll}.
 */
function onERC721Received(
    address,
    address,
    uint256,
    bytes memory
) public virtual override returns (bytes4) {
    return this.onERC721Received.selector;
}

/**
 * @dev See {IERC721Receiver-onERC721Received}.
 *
 * Always returns `IERC721Receiver.onERC721Received.selector`.
 */