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ballot.sol

contract PseudoErc721 {
    public function sunsetLength(uint256) returns (uint256)
}

ballot_test.sol

pragma solidity ^0.4.7;
import "remix_tests.sol"; // this import is automatically injected by Remix.
import "./ballot.sol";

contract test3 {
   
    Ballot ballotToTest;
    function beforeAll () {
       ballotToTest = new Ballot(2);
    }
    
    function checkWinningProposal () public {
        ballotToTest.vote(1);
        Assert.equal(ballotToTest.winningProposal(), uint(1), "1 should be the winning proposal");
    }
    
    function checkWinninProposalWithReturnValue () public constant returns (bool) {
        return ballotToTest.winningProposal() == 1;
    }
}

UnderflowCheck.sol

pragma solidity ^0.4.24;

contract UnderflowCheck {
    uint256 public value;
    constructor(uint256 _value) public {
        require(_value >= 0);
        value = _value;
    }
}