Topic: [INFO]-Crypto Stamps- Collectable Blockchain postage stamps - page 42. (Read 31216 times)

// Upgrade 1 CS2 stamp by "upgrading" with 2 other CS2 of same type and color.
    function upgradeStamp(uint256 _upgradeTokenId, uint256 _helperTokenId1, uint256 _helperTokenId2)

// Upgrade 1 CS2 stamp by "upgrading" with 1 other CS2 of same type and color and 1 CS1 of same color (as a "joker").
    function upgradeStampWithJoker(uint256 _upgradeTokenId, uint256 _helperTokenId, uint256 _helperCS1TokenId)

interface AchievementsUpgradingI is IERC165 {
    /*
     *     Calculate the interface ID for ERC 165:
     *
     *     bytes4(keccak256('onContractAdded(bool)')) == 0x58cac597
     */

    /**
     * @notice Notify about changing a CS2 color as done by the "upgrading" mechanism
     * @dev The Cryptostamp2 smart contract calls this function when changing the color of any asset,
     * esp. as the result of upgrading. This function MUST return the function selector,
     * otherwise the caller will revert the transaction. The selector to be
     * returned can be obtained as `this.onCS2ColorChanged.selector`. This
     * function MAY throw to revert and reject the transfer.
     * Note: the Collection contract address is always the message sender.
     * @param tokenId The token identifier which is being changed
     * @param previousColor The previous color held by the token
     * @param newColor The new color assigned to the token, which MUST match the current color at time of this call
     * @return bytes4 `bytes4(keccak256("onCS2ColorChanged(uint256,uint8,uint8)"))`
     */
    function onCS2ColorChanged(uint256 tokenId, CS2PropertiesI.Colors previousColor, CS2PropertiesI.Colors newColor)
    external returns (bytes4);

}