title: Solve a ValueError
body: <p>I was looking a way to prove my USB-SERIAL port and I found this code:
  <a href="http://www.digitalmihailo.com/usb-programming-with-python-on-linux-pyusb-version/" rel="nofollow">http://www.digitalmihailo.com/usb-programming-with-python-on-linux-pyusb-version/</a>, but I have a problem because when I run this program, then show me up this message:</p>
  
  <pre><code>Traceback (most recent call last):
     File "namefile.py", line 122 in &lt;module&gt;
       main()
     File "namefile.py", line 64, in main
       raise ValueError('Device not found')
  ValueError: Device not found
  </code></pre>
  
  <p>I already install the PyUSB library, but the result does not change. Someone can help me with this little problem.</p>
  
  <p>Thank you much  in advance.</p>