old_contents: #!/usr/bin/env python
  # Copyright (C) 2013-2015  Vincent Pelletier <plr.vincent@gmail.com>
  #
  # This library is free software; you can redistribute it and/or
  # modify it under the terms of the GNU Lesser General Public
  # License as published by the Free Software Foundation; either
  # version 2.1 of the License, or (at your option) any later version.
  #
  # This library is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  # Lesser General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public
  # License along with this library; if not, write to the Free Software
  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  import usb1
  
  def hotplug_callback(context, device, event):
      print "Device %s: %s" % (
          {
              usb1.HOTPLUG_EVENT_DEVICE_ARRIVED: 'arrived',
              usb1.HOTPLUG_EVENT_DEVICE_LEFT: 'left',
          }[event],
          device,
      )
  
  def main():
      with usb1.USBContext() as context:
          if not context.hasCapability(usb1.CAP_HAS_HOTPLUG):
              print 'Hotplug support is missing. Please update your libusb version.'
              return
          opaque = context.hotplugRegisterCallback(hotplug_callback)
          try:
              while True:
                  context.handleEvents()
          except (KeyboardInterrupt, SystemExit):
              pass
  
  if __name__ == '__main__':
      main()
  
new_contents: #!/usr/bin/env python
  # Copyright (C) 2013-2015  Vincent Pelletier <plr.vincent@gmail.com>
  #
  # This library is free software; you can redistribute it and/or
  # modify it under the terms of the GNU Lesser General Public
  # License as published by the Free Software Foundation; either
  # version 2.1 of the License, or (at your option) any later version.
  #
  # This library is distributed in the hope that it will be useful,
  # but WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  # Lesser General Public License for more details.
  #
  # You should have received a copy of the GNU Lesser General Public
  # License along with this library; if not, write to the Free Software
  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  import usb1
  
  def hotplug_callback(context, device, event):
      print "Device %s: %s" % (
          {
              usb1.HOTPLUG_EVENT_DEVICE_ARRIVED: 'arrived',
              usb1.HOTPLUG_EVENT_DEVICE_LEFT: 'left',
          }[event],
          device,
      )
  
  def main():
      with usb1.USBContext() as context:
          if not context.hasCapability(usb1.CAP_HAS_HOTPLUG):
              print 'Hotplug support is missing. Please update your libusb version.'
              return
          print 'Registering hotplug callback...'
          opaque = context.hotplugRegisterCallback(hotplug_callback)
          print 'Callback registered. Monitoring events, ^C to exit'
          try:
              while True:
                  context.handleEvents()
          except (KeyboardInterrupt, SystemExit):
              print 'Exiting'
  
  if __name__ == '__main__':
      main()
  
subject: Increase verbosity.