Write a method called is1to1 that accepts a map whose keys and valuesare strings as its parameter and returns true if no two keys map to thesame value. for example, {marty=206–9024, hawking=123–4567,smith=949–0504, newton=123–4567} should return false, but{marty=206–9024, hawking=555–1234, smith=949–0504,newton=123–4567} should return true. the empty map is considered 1-to-1 and returns true.