Sample OpenZeppelin NFT

MyNFT.sol

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/security/Pausable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";

contract MyNFT is ERC721URIStorage, Pausable, Ownable {
    using Counters for Counters.Counter;

    string local_baseURI;

    Counters.Counter private _tokenIdCounter;

    constructor() ERC721("MPage's NFT", "MPSK") {
        _tokenIdCounter.increment();
        local_baseURI = "https://nft.mpage.sk/meta.php?n=";
    }

    function _baseURI() internal view override returns (string memory) {
        return local_baseURI;
    }

    function changeBaseURI(string memory baseURI) public onlyOwner {
        local_baseURI = baseURI;
    }

    function totalSupply() view public returns(uint){
        return _tokenIdCounter.current()-1;
    }

    function ownerOfToken(uint id) view public returns(bool){
        return ownerOfToken(id);
    }

    function pause() public onlyOwner {
        _pause();
    }

    function unpause() public onlyOwner {
        _unpause();
    }


    function safeMint() public {
        _safeMint(msg.sender, _tokenIdCounter.current());
        _tokenIdCounter.increment();
    }

    function changeTokenURI(string memory uri, uint id) public onlyOwner {
        _setTokenURI(id,uri);
    }

    function _beforeTokenTransfer(address from, address to, uint256 tokenId)
    internal
    whenNotPaused
    override
    {
        super._beforeTokenTransfer(from, to, tokenId);
    }
}