  bytes4 public constant JOIN = bytes4(keccak256("join(address,uint128)"));
  bytes4 public constant EXIT = bytes4(keccak256("exit(address,uint128)"));
  bytes4 public constant MINT = bytes4(keccak256("mint(address,uint256)"));
  bytes4 public constant BURN = bytes4(keccak256("burn(address,uint256)"));

  _grantRole(IEmergencyBrake.plan.selector, planner);
