Semaphore class and instance methods

The class methods for Semaphore include the following:

forMutualExclusion

Answers a new semaphore that has one signal.

new

Answers a new semaphore that has no signals.

The instance methods include the following:

critical:

Evaluates the argument block and guarantees that there will be no context switch while the block is being evaluated.

signal

Adds a signal to the receiver.

wait

Suspends the active process until there is a signal available from the receiver.