Resume the receiver’s execution
Execute a limited amount of code (usually a bytecode, or up to the next backward jump, or up to the next message send) of the receiver, which must in a ready-to-run state (neither executing nor terminating nor suspended), then restart running the current process. aSemaphore is used as a means to synchronize the execution of the current process and the receiver and should have no signals on it. The current process should have higher priority than the receiver.
Do nothing if we’re already suspended. Note that the blue book made suspend a primitive - but the real primitive is yielding control to another process. Suspending is nothing more than taking ourselves out of every scheduling list and THEN yielding control to another process
Yield control from the receiver to other processes