if (_isEventRegistered(HolographERC20Event.beforeSafeTransfer)) {
  require(SourceERC20().beforeSafeTransfer(account, recipient, amount, data));
}
_transfer(account, recipient, amount);
require(_checkOnERC20Received(account, recipient, amount, data), "ERC20: non ERC20Receiver");
if (_isEventRegistered(HolographERC20Event.afterSafeTransfer)) {
  require(SourceERC20().afterSafeTransfer(account, recipient, amount, data));
}
if (_isContract(recipient)) {
  try ERC165(recipient).supportsInterface(ERC165.supportsInterface.selector) returns (bool erc165support) {
    require(erc165support, "ERC20: no ERC165 support");
    // we have erc165 support
    if (ERC165(recipient).supportsInterface(0x534f5876)) {
      // we have eip-4524 support
      try ERC20Receiver(recipient).onERC20Received(address(this), account, amount, data) returns (bytes4 retv
        return retval == ERC20Receiver.onERC20Received.selector;
      } catch (bytes memory reason) {
        if (reason.length == 0) {
          revert("ERC20: non ERC20Receiver");
        } else {
          assembly {
            revert(add(32, reason), mload(reason))
          }
        }
      }
    } else {
      revert("ERC20: eip-4524 not supported");
    }
  } catch (bytes memory reason) {
    if (reason.length == 0) {
      revert("ERC20: no ERC165 support");
    } else {
      assembly {
        revert(add(32, reason), mload(reason))
      }
    }
  }
} else {
  return true;
}
 This EIP is not recommended for general use or implementation as it is likely to change.
