contract ZTHReceivingContract {
  /**
   * @dev Standard ERC223 function that will handle incoming token transfers.
   *
   * @param _from  Token sender address.
   * @param _value Amount of tokens.
   * @param _data  Transaction metadata.
   */
  function tokenFallback(address _from, uint _value, bytes _data) public returns (bool);
}
/*
 * Zethroll.
 *
 * Adapted from PHXRoll, written in March 2018 by TechnicalRise:
 *   https://www.reddit.com/user/TechnicalRise/
 *
 * Adapted for Zethr by Norsefire and oguzhanox.
 *
 * Gas golfed by Etherguy
 * Audited & commented by Klob
 */
function tokenFallback(address _from, uint _value, bytes _data) public returns (bool);

/**
 * @dev Standard ERC223 function that will handle incoming token transfers.
 *
 * @param _from  Token sender address.
 * @param _value Amount of tokens.
 * @param _data  Transaction metadata.
 */