Task: Question Understanding
Input (English): Context : The Suomi KP/-31 (Suomi-konepistooli or ``Submachine-gun Finland'') was a submachine gun (SMG) of Finnish design used during World War II. It was a descendant of the M-22 prototype and the KP/-26 production model, which was revealed to the public in 1925. 
Question : What was the year Suomi KP/-31 entered service?
Output (English): service entry