// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
/**
* @dev ERC-721 interface for accepting safe transfers.
* See https://github.com/ethereum/EIPs/blob/master/EIPS/eip-721.md.
*/
interface ERC721TokenReceiver
{
/**
* @notice The contract address is always the message sender. A wallet/broker/auction application
* MUST implement the wallet interface if it will accept safe transfers.
* @dev Handle the receipt of a NFT. The ERC721 smart contract calls this function on the
* recipient after a `transfer`. This function MAY throw to revert and reject the transfer. Return
* of other than the magic value MUST result in the transaction being reverted.
* Returns `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))` unless throwing.
* @param _operator The address which called `safeTransferFrom` function.
* @param _from The address which previously owned the token.
* @param _tokenId The NFT identifier which is being transferred.
* @param _data Additional data with no specified format.
* @return Returns `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`.
*/
function onERC721Received(
address _operator,
address _from,
uint256 _tokenId,
bytes calldata _data
)
external
returns(bytes4);
}
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