Represents a counting semaphore.

make initial creates a new counting semaphore with the given initial count.

• raises Invalid_argument

  in case the given initial count is negative.

release semaphore increments the count of the semaphore.

• raises Sys_error

  in case the count would overflow.

acquire semaphore waits until the count of the semaphore is greater than 0 and then atomically decrements the count.

try_acquire semaphore attempts to atomically decrement the count of the semaphore unless the count is already 0.

get_value semaphore returns the current count of the semaphore. This should only be used for debugging or informational messages.