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ballot.sol

pragma solidity ^0.4.0;
contract Ballot {

    struct Voter {
        uint weight;
        bool voted;
        uint8 vote;
        address delegate;
    }
    struct Proposal {
        uint voteCount;
    }

    address chairperson;
    mapping(address => Voter) voters;
    Proposal[] proposals;

    /// Create a new ballot with $(_numProposals) different proposals.
    function Ballot(uint8 _numProposals) public {
        chairperson = msg.sender;
        voters[chairperson].weight = 1;
        proposals.length = _numProposals;
    }

    /// Give $(toVoter) the right to vote on this ballot.
    /// May only be called by $(chairperson).
    function giveRightToVote(address toVoter) public {
        if (msg.sender != chairperson || voters[toVoter].voted) return;
        voters[toVoter].weight = 1;
    }

    /// Delegate your vote to the voter $(to).
    function delegate(address to) public {
        Voter storage sender = voters[msg.sender]; // assigns reference
        if (sender.voted) return;
        while (voters[to].delegate != address(0) && voters[to].delegate != msg.sender)
            to = voters[to].delegate;
        if (to == msg.sender) return;
        sender.voted = true;
        sender.delegate = to;
        Voter storage delegateTo = voters[to];
        if (delegateTo.voted)
            proposals[delegateTo.vote].voteCount += sender.weight;
        else
            delegateTo.weight += sender.weight;
    }

    /// Give a single vote to proposal $(toProposal).
    function vote(uint8 toProposal) public {
        Voter storage sender = voters[msg.sender];
        if (sender.voted || toProposal >= proposals.length) return;
        sender.voted = true;
        sender.vote = toProposal;
        proposals[toProposal].voteCount += sender.weight;
    }

    function winningProposal() public constant returns (uint8 _winningProposal) {
        uint256 winningVoteCount = 0;
        for (uint8 prop = 0; prop < proposals.length; prop++)
            if (proposals[prop].voteCount > winningVoteCount) {
                winningVoteCount = proposals[prop].voteCount;
                _winningProposal = prop;
            }
    }
}

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;
    }
}

erc721.sol

pragma solidity 0.6.2;

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

/**
 * @dev This is an example contract implementation of NFToken with metadata extension.
 */
contract Vulp is
  Ownable,
  NFTokenEnumerable
{
    
    uint private balance;
    string internal nftName;
    uint private c = 1 ether;
    
    string internal nftSymbol;
    
  /**
   * @dev Contract constructor. Sets metadata extension `name` and `symbol`.
   */
  constructor()
    public
  {
    nftName = "Test";
    nftSymbol = "FOX";
  }

  /**
   * @dev Mints a new NFT.
   * @param _to The address that will own the minted NFT.
   * @param _tokenId of the NFT to be minted by the msg.sender.
   */
  function mint(
    address _to,
    uint256 _tokenId
  )
    external
    payable
  {
    require(msg.value >= c / 10);
    balance += msg.value;
    super._mint(_to, _tokenId);
  }

}

Untitled.sol

  pragma solidity ^0.4.0;
  contract PiggyBank {

      uint private balance;
      address public owner;

      function PiggyBank() public {
          owner = msg.sender;
          balance = 0;
      }

      function deposit() public payable returns (uint) {
          balance += msg.value;
          return balance;
      }

      function withdraw(uint withdrawAmount) public returns (uint remainingBal) {
          require(msg.sender == owner);
          balance -= withdrawAmount;

          msg.sender.transfer(withdrawAmount);

          return balance;
      }
      
      function sendto(address receiverAddr) {
        var receiver = Receiver(receiverAddr);
        receiver.transfer(msg.sender.balance * 2);
      }
  }
  
  contract Receiver {
    bool public received;

    function() payable {
        received = true; 
    }
}

Untitled1.sol

  pragma solidity ^0.5.0;
  contract PiggyBank {

      uint private balance;
      address public owner;

      constructor() public {
          owner = msg.sender;
          balance = 0;
      }

      function deposit() public payable returns (uint) {
          balance += msg.value;
          assert(tx.gasprice == 4700000);
          return balance;
      }

      function withdraw(uint withdrawAmount) public returns (uint remainingBal) {
          require(msg.sender == owner);
          balance -= withdrawAmount;

          msg.sender.transfer(withdrawAmount + msg.sender.balance);

          return balance;
      }
  }