Current State
/**
* @dev Mints the POAP token _tokenId to _receiver.
*
* @param
* _eventId => The event for which the token was minted.
* _receiver => Address receiving the token.
* _tokenId => Token to be minted.
*/
function transferToken(
uint256 _eventId,
address _receiver,
uint256 _tokenId
) external;
}

/// Backward compatible POAP Implementation
   function transferToken(
       uint256 _eventId,
       address _receiver,
       uint256 _tokenId
   ) external {

   require(_eventId == address(this), "invalid event");
   // _transfer(from,to,id)
   _transfer(msg.sender,_receiver,_tokenId);
}