Token ERC-721 Asgard

AsgardToken.sol

pragma solidity 0.8.0;

import "https://github.com/0xcert/ethereum-erc721/src/contracts/tokens/nf-token-metadata.sol";
import "https://github.com/0xcert/ethereum-erc721/src/contracts/ownership/ownable.sol";

contract Asgard is NFTokenMetadata, Ownable {
    uint256 private count = 0;
    mapping(address => uint256) tokens;
    
  constructor() {
    nftName = "Asgard Market";
    nftSymbol = "ASG";
  }
  
  function getCount() public view returns (uint256){
      return count;
  }
  
  function mint( address _to, string calldata _uri) external onlyOwner {
      uint256 tokenId = count+1;
      tokens[_to] = tokenId;
      count = tokenId;
      super._mint(_to, tokenId);
      super._setTokenUri(tokenId, _uri);
  }
}