#include "unify.h"
int Read_Count(int event_id);
Read_Count(3) returns the current value of the event
counter referenced by event_id.
Read_Count(3) returns the current value of the event
counter referenced by event_id on successful completion.
Otherwise, a value of -1 is returned.
An error may occur if event_id is not a valid event identifier.
The value of the event counter may have changed by the time
Read_Count(3) returns.