pragma solidity ^0.4.24;

import "openzeppelin-solidity/contracts/introspection/ERC165.sol";

contract IActivityObject is ERC165 {
    bytes4 internal constant InterfaceId_IActivityObject = 0x2b9eccc6; 
    /*
     * 0x2b9eccc6 ===
     *   bytes4(keccak256('activityAdded(uint256,address,address)')) ^ 
     *   bytes4(keccak256('activityRemoved(uint256,address,address)'))
     */

    function activityAdded(uint256 _tokenId, address _activity, address _user) public;

    function activityRemoved(uint256 _tokenId, address _activity, address _user) public;
}