boundedSub(uint256 a, uint256 b) → uint256 internalboundedSubWithoutEvent(uint256 a, uint256 b) → uint256 internalmuchGreater(uint256 a, uint256 b) → bool internalapproximatelyEqual(uint256 a, uint256 b) → bool internalUnderflowError(uint256 a, uint256 b) event