pragma solidity 0.4.24;

contract Naive {
    event Batch();

    // This function is called for all messages sent to
    // this contract (there is no other function).
    // Sending Ether to this contract will cause an exception,
    // because the fallback function does not have the `payable`
    // modifier.
    //
    function() external {
        emit Batch();
    }
}