Add :values_at to Harray

lib/shotengai/harray.rb

@@ -34,6 +34,10 @@ module Shotengai
       nil
     end
 
+    def values_at *keys
+      self.reduce([]) { |output, obj| output << obj.last if obj.first.in?(keys) }
+    end
+
     def decode
       self.map{ |obj| { obj['key'] => obj['val'] } }.reduce(&:merge)
     end