human
Solve the following python programming problem given the following code:
def __getattr__(self, attr) : 
    'Fallthrough to underlying FastbootProtocol handler.

    Args:
      attr: Attribute to get.
    Returns:
      Either the attribute from the device or a retrying function-wrapper
      if attr is a method on the device.
    ' 
    if (not attr._protocol) : 
        raise usb_exceptions.HandleClosedError () 
val = getattr (self._protocol, attr) 
    if callable (val) : 
        def _retry_wrapper(* args, **kwargs) : 
            'Wrap the retry function.' 
            result = _retry_usb_function (self._num_retries, val, * args, ** kwargs) 
            _LOG.debug ('LIBUSB FASTBOOT: %s(*%s, **%s) -> %s', attr, args, kwargs, result) 
            return result 
return _retry_wrapper 
return val 

    
    

    Fix the buggy line: if (not attr._protocol) :
assistant
#Here is Python program to fix the buggy line: if (not attr.

if (not self._protocol) :