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gist-195b27a40656c46924421efad787e297...contracts...subquest-erc-721.sol

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";

contract YourCollectible is ERC721URIStorage {
    
    string NAME = "Abstract Collectibles";
    string SYMBOL = "ABS";
    uint256 private _tokenId = 1;
    
    // this marks an item as "forsale"
    mapping (string => bool) public forSale;

    constructor(string memory assetForSale) public ERC721(NAME, SYMBOL) {
        forSale[assetForSale] = true;
    }

    function mintItem(string memory tokenURI) external returns (uint256) {
        // only "forsale" items are up for minting
        require(forSale[tokenURI],"NOT FOR SALE");
        forSale[tokenURI] = false;

        _mint(msg.sender, _tokenId);

        // set tokenURI for plugging in our metadata to NFT
        _setTokenURI(_tokenId, tokenURI);

        return _tokenId;
    }
}