code: def devno_free_if_allocated(self, devno):
          
          devno_int = int(devno, 16)
          self._devno_pool.free_if_allocated(devno_int)
docs: Free a device number allocated with :meth:`devno_alloc`.
  
          If the device number is not currently allocated or not in the pool
          range, nothing happens.
  
          Parameters:
            devno (string): The device number as four hexadecimal digits.