takeOrders -> _takeOrders -> _execTakeOrders -> _transferNFTsAndFees -> _transferFees
takeMultipleOneOrders -> _execTakeOneOrder -> _transferNFTsAndFees -> _transferFees
  /**
   * @notice Transfer fees. Fees are always transferred from buyer to the seller and the exchange although seller is 
            the one that actually 'pays' the fees
   * @dev if the currency ETH, no additional transfer is needed to pay exchange fees since the contract is 'payable'
   * @param seller the seller
   * @param buyer the buyer
   * @param amount amount to transfer
   * @param currency currency of the transfer
   */
  function _transferFees(
    address seller,
    address buyer,
    uint256 amount,
    address currency
  ) internal {
    // protocol fee
    uint256 protocolFee = (PROTOCOL_FEE_BPS * amount) / 10000;
    uint256 remainingAmount = amount - protocolFee;
    // ETH
    if (currency == address(0)) {
      // transfer amount to seller
      (bool sent, ) = seller.call{value: remainingAmount}('');
      require(sent, 'failed to send ether to seller');
  /// @dev used for rescuing exchange fees paid to the contract in ETH
  function rescueETH(address destination) external payable onlyOwner {
    (bool sent, ) = destination.call{value: msg.value}('');
    require(sent, 'failed');
  }
  /// @dev used for rescuing exchange fees paid to the contract in ETH
  function rescueETH(address destination) external payable onlyOwner {
-   (bool sent, ) = destination.call{value: msg.value}('');
+   (bool sent, ) = destination.call{value: address(this).balance}('');
    require(sent, 'failed');
  }
