title: Finding only disk drives using pyudev
body: <p>I'm looking to enumerate all hard disks on a computer using udev and specifically pyudev to enumerate everything:</p>
  
  <pre><code>import pyudev
  
  context = pyudev.Context()
  
  for device in context.list_devices(subsystem='block', DEVTYPE='disk'):
      print "{}, ({})".format(device.device_node, device.device_type)
  </code></pre>
  
  <p>This prints out the following:</p>
  
  <pre><code>/dev/sdb (disk)
  /dev/sdc (disk)
  /dev/sda (disk)
  /dev/sr0 (disk)
  /dev/loop0 (disk)
  /dev/loop1 (disk)
  /dev/loop2 (disk)
  /dev/loop3 (disk)
  /dev/loop4 (disk)
  /dev/loop5 (disk)
  /dev/loop6 (disk)
  /dev/loop7 (disk)
  /dev/ram0 (disk)
  /dev/ram1 (disk)
  /dev/ram10 (disk)
  /dev/ram11 (disk)
  /dev/ram12 (disk)
  /dev/ram13 (disk)
  /dev/ram14 (disk)
  /dev/ram15 (disk)
  /dev/ram2 (disk)
  /dev/ram3 (disk)
  /dev/ram4 (disk)
  /dev/ram5 (disk)
  /dev/ram6 (disk)
  /dev/ram7 (disk)
  /dev/ram8 (disk)
  /dev/ram9 (disk)
  </code></pre>
  
  <p>Since I'm mainly concerned with actual drives and not optical disk drives, loopback devices, or ram devices, how can I filter my results down to only get real physical media?</p>