Blocks a handler of an instance so it will not be called during any signal emissions unless it is unblocked again. Thus “blocking” a signal handler means to temporarily deactivate it, a signal handler has to be unblocked exactly the same amount of times it has been blocked before to become active again.
handler_id has to be a valid signal handler id, connected to a
The instance to block the signal handler of.
The data is owned by the caller of the function.
Handler id of the handler to be blocked.