def sync_keys(dsk1, dsk2):
 return _sync_keys(dsk1, dsk2, toposort(dsk2))

def sync_keys ( dsk1 , dsk2 ) : return _sync_keys ( dsk1 , dsk2 , toposort ( dsk2 ) )
return a dict matching keys in dsk2 to equivalent keys in dsk1 .