What are the beginning and end dates of the administration of Arthur B. Langlie as Mayor of Seattle?
SELECT ?value1 ?value2 WHERE { wd:Q5083 p:P6 ?s . ?s ps:P6 wd:Q371494 . ?s pq:P2031 ?value1 . ?s pq:P2032 ?value2 }
seattle: Q5083 arthur b. langlie: Q371494