# File lib/fog/cloudstack/models/compute/volume.rb, line 81
        def attach(instance_or_id, mountpoint=nil)
          requires :id
          instance_id = instance_or_id.is_a?(Server) ? instance_or_id.id : instance_or_id
          unless instance_id
            raise ArgumentError, "Missing required argument: instance_or_id"
          end

          options = {
            'id'               => id,
            'virtualmachineid' => instance_id,
          }
          options.merge!('deviceid' => mountpoint) if mountpoint

          data = service.attach_volume(options)

                                        service.jobs.new(data["attachvolumeresponse"])
        end