title: PyUSB: No backend available
body: <p>I'm trying to reach out and find what USB devices are tied to my computer. I'm going through the "Programming with PyUSB 1.0" tutorial. I can't get anything I'm using there to work, I keep getting a "ValueError: No background available" error. What is missing from my code? I'm on a 64 bit Windows 10 machine. I installed the libusb1 package as well as the pylibusb package.</p>
  
  <pre><code>import usb
  import usb.core
  import usb.util
  import sys
  
  devices = usb.core.find(find_all=True)
  
  sys.stdout.write('There are ' + len(devices) + ' in the system\n.')
  </code></pre>