 [det]pengine_event(?EventTerm)
[det]pengine_event(?EventTerm, 
+Options)Examines the pengine's event queue and if necessary blocks execution 
until a term that unifies to Term arrives in the queue. After a term 
from the queue has been unified to Term, the term is deleted from the 
queue.
[det]pengine_event(?EventTerm)
[det]pengine_event(?EventTerm, 
+Options)Examines the pengine's event queue and if necessary blocks execution 
until a term that unifies to Term arrives in the queue. After a term 
from the queue has been unified to Term, the term is deleted from the 
queue.
Valid options are:
- timeout(+Time)
- Time is a float or integer and specifies the maximum time to 
wait in seconds. If no event has arrived before the time is up EventTerm 
is bound to the atom timeout.
- listen(+Id)
- Only listen to events from the pengine identified by Id.