human
Solve the following python programming problem given the following code:
def _canonicalize_query(self, query) : 
    '
        Transform the query dictionary to replace e.g. documents with __ref__ fields.
        ' 
    def transform_query(q) : 
        for encoder in self.query_encoders : 
            q = encoder.encode (q, []) 
if isinstance (q, dict) : 
            nq = { 
                
} 
            for (key, value) in q.items () : 
                new_key = key 
                if (isinstance (value, dict) and (len (value) == 1) and list (value.keys ()) [0].startswith ('$')) : 
                    if (list (value.keys ()) [0] in ('$all', '$in')) : 
                        if (list (value.values ()) [0] and isinstance (list (value.values ()) [0] [0], Document)) : 
                            if self._use_pk_based_refs : 
                                new_key += '.pk' 
else : 
                                new_key += '.__ref__' 
else : 
                    if isinstance (value, Document) : 
                        if self._use_pk_based_refs : 
                            new_key += '.pk' 
else : 
                            new_key += '.__ref__' 
nq [new_key] = transform_query (value) 
return nq 
else : 
            if isinstance (q, (list, QuerySet, tuple)) : 
                return [transform_query (x) for x in q] 
else : 
                if isinstance (q, Document) : 
                    collection = self.get_collection_for_obj (q) 
                    if self._use_pk_based_refs : 
                        return q.pk 
else : 
                        return ('%s:%s' % (collection, q.pk)) 
else : 
                    return q 
return transform_query (self) 

    
    

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

return transform_query (query)