Вызов метода смарт контракта с другого контракта

Например есть контракт токена (MyToken) написанный на Solidity. Хочу вызвать метод balanceOf контракта MyToken с другого контракта (Game). Я не давно начал изучать Solidity и попробовал несколько способов но без успешно((. Ниже пример моего кода:

pragma solidity 0.4.21;

interface InterfaceExample {
    // mind the `view` modifier
    function balanceOf(address _address) external view returns (uint);
}
contract MyToken is InterfaceExample {
  using SafeMath for uint;

  string public constant name = "MyToken";
  string public constant symbol = "MFT";
  uint public constant decimals = 2;
  address private creator;

  uint public totalSupply;

  mapping(address => uint) balances;
  mapping(address => mapping(address => uint)) allowed;

  event Transfer(address indexed _from, address indexed _to, uint _value);
  event Approval(address indexed _from, address indexed _to, uint _value);

  modifier isCreator() {
    require(creator == msg.sender);
    _;
  }

  function MyToken() public {
    creator = msg.sender;
  }

  function mint(address _to, uint _value) public isCreator {
    balances[_to] = balances[_to].add(_value);
    totalSupply = totalSupply.add(_value);
  }

  function balanceOf(address _address) external view returns(uint) {
    return balances[_address];
  }

  function transfer(address _to, uint _value) public {
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    emit Transfer(msg.sender, _to, _value);
  }

  function transferFrom(address _from, address _to, uint _value) public {
    require(balances[_from] >= _value && allowed[_from][msg.sender] >= _value);
    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    emit Transfer(_from, _to, _value);
  }

  function approve(address _spender, uint _value) public {
    allowed[msg.sender][_spender] = _value;
    emit Approval(msg.sender, _spender, _value);
  }

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

contract Game {
    address owner = 0x5B38Da6a701c568545dCfcB03FcB875f56beddC4;
    address public addr = address(this); 
    InterfaceExample obj;
    
    function Game() public {
        obj = MyToken(0x38cB7800C3Fddb8dda074C1c650A155154924C73);
    }
    
    function getBalance() external view returns(uint){
        return obj.balanceOf(msg.sender);
    }
}