human
Solve the following python programming problem given the following code:
@ app.route ('/VolumeDriver.List', methods = ['POST']) 
@ _endpoint ('List') 
def volumedriver_list(self) : 
    '
        Return information about the current state of all volumes.

        :return: Result indicating success.
        ' 
    listing = DeferredContext (self._flocker_client.list_datasets_configuration ()) 
    def got_configured(configured) : 
        results = [] 
        for dataset in configured : 
            if (NAME_FIELD not in dataset.metadata) : 
                continue 
dataset_name = dataset.metadata [NAME_FIELD] 
            d = self._get_path_from_dataset_id (dataset.dataset_id) 
            d.addCallback ((lambda path, name = dataset_name : (path, name))) 
            results.append (d) 
return gatherResults (results) 
listing.addCallback (self) 
    def got_paths(results) : 
        return { 
            'Err' : '', 
            'Volumes' : sorted ([{ 
                'Name' : name, 
                'Mountpoint' : ('' if (path is None) else path.path), 
} for (path, name) in results]), 
} 
listing.addCallback (got_paths) 
    return listing.result 

    
    

    Fix the buggy line: listing.addCallback (self)
assistant
#Here is Python program to fix the buggy line: listing.

listing.addCallback (def got_configured()