def devices
      devices = @adb.devices.map { |d|
        serial = d.serial_number
        (@devices.has_key?(serial) && same_jobject?(@devices[serial].jobject, d)) \
          ? @devices[serial] : Device.new(d)
      }
      @devices = DeviceList.new(devices)
      return @devices
    end
def devices
      devices = @adb.devices.map { |d|
        serial = d.serial_number
        (@devices.has_key?(serial) && same_jobject?(@devices[serial].jobject, d)) \
          ? @devices[serial] : Device.new(d)
      }
      @devices = DeviceList.new(devices)
      return @devices
    end
Get devices attached with ADB.
 @return [DeviceList] List of devices