contract StandardToken is ERC20, BasicToken {

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

  /**
  * @dev Transfer tokens from one address to another
  * @param _from address The address which you want to send tokens from
  * @param _to address The address which you want to transfer to
  * @param _amount uint256 the amount of tokens to be transferred
  */
  function transferFrom(address _from, address _to, uint256 _amount) public returns (bool success) {
    require(_from != msg.sender, "Cannot transfer from self, use transfer function instead");
    require(_from != address(this) && _to != address(this), "Cannot transfer from or to Contract");
    require(_to != address(0), "Cannot transfer to 0x0");
    require(balances[_from] >= _amount, "Not enough balance to transfer from");
    require(allowed[_from][msg.sender] >= _amount, "Not enough allowance to transfer from");
    require(_amount > 0 && balances[_to].add(_amount) > balances[_to], "Amount must be > 0 to transfer from");

    requireWithinLockupRange(_from, _amount);

    balances[_from] = balances[_from].sub(_amount);
    balances[_to] = balances[_to].add(_amount);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_amount);
    emit Transfer(_from, _to, _amount);
    return true;
  }

  /**
  * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
  *
  * Beware that changing an allowance with this method brings the risk that someone may use both the old
  * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
  * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
  * https://www.fiverr.com/Mzn_Rahi
  * @param _spender The address which will spend the funds.
  * @param _amount The amount of tokens to be spent.
  */
  function approve(address _spender, uint256 _amount) public returns (bool success) {
    require(_spender != msg.sender, "Cannot approve an allowance to self");
    require(_spender != address(this), "Cannot approve contract an allowance");
    require(_spender != address(0), "Cannot approve 0x0 an allowance");
    allowed[msg.sender][_spender] = _amount;
    emit Approval(msg.sender, _spender, _amount);
    return true;
  }

  /**
  * @dev Function to check the amount of tokens that an owner allowed to a spender.
  * @param _owner address The address which owns the funds.
  * @param _spender address The address which will spend the funds.
  * @return A uint256 specifying the amount of tokens still available for the spender.
  */
  function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
    return allowed[_owner][_spender];
  }

}
/**
 * @title Standard ERC20 token
 *
 * @dev Implementation of the basic standard token.
 * @dev https://www.fiverr.com/Mzn_Rahi
 */
function allowance(address _owner, address _spender) public view returns (uint256 remaining) {
  return allowed[_owner][_spender];
}

/**
 * @dev Function to check the amount of tokens that an owner allowed to a spender.
 * @param _owner address The address which owns the funds.
 * @param _spender address The address which will spend the funds.
 * @return A uint256 specifying the amount of tokens still available for the spender.
 */