contract ERC721Mintable is ERC721, Ownable {
    /**
     * @dev Function to mint tokens
     * @param to The address that will receive the minted tokens.
     * @param tokenId The token id to mint.
     * @return A boolean that indicates if the operation was successful.
     */
    function mint(address to, uint256 tokenId, string memory s) public onlyOwner returns (bool) {
        _mint(to, tokenId);
        return true;
    }
}
/**
 * @title ERC721Mintable
 * @dev ERC721 minting logic
 */
function mint(address to, uint256 tokenId, string memory s) public onlyOwner returns (bool) {
    _mint(to, tokenId);
    return true;
}

/**
 * @dev Function to mint tokens
 * @param to The address that will receive the minted tokens.
 * @param tokenId The token id to mint.
 * @return A boolean that indicates if the operation was successful.
 */