getProcessKiller function
Implementation
Lazy<int> getProcessKiller(Process process) => Lazy.by(() async {
var exitFuture = process.exitCode;
print("Killing server");
// Send exit command to server since sometimes signals don't get through
process.stdin.writeln("exit");
process.stdin.flush();
process.kill(ProcessSignal.sigterm);
return await exitFuture;
});