code: def open(self):
          
          self.h_info = SetupDiGetClassDevs(byref(self.guid), None, None,
                  (DIGCF.PRESENT | DIGCF.DEVICEINTERFACE) )
  
          return self.h_info
docs: Calls SetupDiGetClassDevs to obtain a handle to an opaque device
          information set that describes the device interfaces supported by all
          the USB collections currently installed in the system. The
          application should specify DIGCF.PRESENT and DIGCF.INTERFACEDEVICE
          in the Flags parameter passed to SetupDiGetClassDevs.