code: def open(self):
          
          assert self.__context_refcount == 0
          mayRaiseUSBError(libusb1.libusb_init(byref(self.__context_p)))
          return self
docs: Finish context initialisation, as is normally done in __enter__ .
  
          This happens automatically on the first method call needing access to
          the uninitialised properties, but with a warning.
          Call this method ONLY if your usage pattern prevents you from using the
              with USBContext() as contewt:
          form: this means there are ways to avoid calling close(), which can
          cause issues particularly hard to debug (ex: interpreter hangs on
          exit).