Universe of Hyperlink

pragma solidity >=0.4.22 <0.7.0;

import './erc20interface.sol';

contract ERC20 is ERC20Interface {


    string public  name;
    string public constant symbol = "UNN";
    uint8 public constant decimals = 18; 

    
     uint public totalSupply;
     
    mapping(address => uint256) internal _balances;

    mapping(address => mapping(address => uint256)) allowed;

    constructor(string memory _name) public {
       name = _name;  
       totalSupply = 150000000 * 10 ** uint256(decimals);
       _balances[msg.sender] = totalSupply;
    }

    function balanceOf(address tokenOwner) public view returns (uint balance) {
        return _balances[tokenOwner];
    }

  function transfer(address _to, uint256 _value)  public returns (bool success) {
      require(_to != address(0));
      require(_balances[msg.sender] >= _value);
      require(_balances[ _to] + _value >= _balances[ _to]);   


      _balances[msg.sender] -= _value;
      _balances[_to] += _value;

      emit Transfer(msg.sender, _to, _value);

      return true;
  }


  function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
      require(_to != address(0));
      require(allowed[_from][msg.sender] >= _value);
      require(_balances[_from] >= _value);
      require(_balances[ _to] + _value >= _balances[ _to]);

      _balances[_from] -= _value;
      _balances[_to] += _value;

      allowed[_from][msg.sender] -= _value;

      emit Transfer(msg.sender, _to, _value);
      return true;
  }

  function approve(address _spender, uint256 _value) public returns (bool success) {
      allowed[msg.sender][_spender] = _value;

      emit Approval(msg.sender, _spender, _value);
      return true;
  }

  function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
      return allowed[_owner][_spender];
  }

}

pragma solidity >=0.4.22 <0.7.0;

contract ERC20Interface {

    function balanceOf(address tokenOwner) external view returns (uint balance);

    function allowance(address tokenOwner, address spender) external view returns (uint remaining);
    function approve(address spender, uint tokens) external returns (bool success);

    function transfer(address to, uint tokens) external returns (bool success);
    function transferFrom(address from, address to, uint tokens) public returns (bool success);


    event Transfer(address indexed from, address indexed to, uint tokens);
    event Approval(address indexed tokenOwner, address indexed spender, uint tokens);
}

{
  "compilationTarget": {
    "erc20.sol": "ERC20"
  },
  "evmVersion": "petersburg",
  "libraries": {},
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}