Validate Ufunction

What does the _validate function actually do? When i am making a function for the server, you have to add a _validate function. But, what should actually go inside that function?

This is used for cheating or hacking, like you detect some invalid RPC call, with some value not suppose to be there, or it’s not supposed to be called at that moment, then if you return false it will terminate the client connection to server right away.