    # File lib/fog/virtual_box/models/compute/storage_controller.rb, line 23
            def attach(medium, port, device = 0)
              requires :identity, :machine
              with_session do |session|
                session.machine.attach_device(identity, port, device, medium.device_type, medium.instance_variable_get(:@raw))
                session.machine.save_settings
              end
              true
            end