# File lib/mongo/protocol/update.rb, line 190
        def command
          document = BSON::Document.new
          updates = BSON::Document.new
          updates.store(Message::Q, filter)
          updates.store(U, update)
          updates.store(MULTI, flags.include?(:multi_update))
          updates.store(UPSERT, flags.include?(:upsert))
          document.store(UPDATE, collection)
          document.store(Message::ORDERED, true)
          document.store(UPDATES, [ updates ])
          document
        end