I suspect that the Arduino object is not getting created because you are not supplying the correct COM port number while creating the object. The following documentation gives you an idea about how to find COM ports on different operating systems.
As you are on Linux OS, perform the following steps with Arduino not plugged into computer.
1) Run the following command on terminal:
$ ls /dev/tty*
This will list all the serial devices.
2) Plug in the Arduino and repeat Step 1. You will see an additional entry in the list displayed. This is the argument you must supply to COM port while creating Arduino object.
For additional information you can refer to documentation.
