constructor(
    ERC20Basic _token,
    uint256 _totalFunds,
    uint256 _releaseDate
  ) public validAddress(_token) {
    require(_totalFunds > 0);
    
    require(_releaseDate > block.timestamp);

    token = _token;
    totalFunds = _totalFunds;
    distributedTokens = 0;
    releaseDate = _releaseDate;
  }