human
Solve the following python programming problem given the following code:
def _validate_pk(model, table_meta) : 
    model_partition = [c.db_field_name for c in model._partition_keys.values ()] 
    meta_partition = [c.name for c in table_meta.partition_key] 
    model_clustering = [c.db_field_name for c in model._clustering_keys.values ()] 
    meta_clustering = [c.name for c in table_meta.clustering_key] 
    if ((model_partition != meta_partition) or (model_clustering != meta_clustering)) : 
        def _pk_string(partition, clustering) : 
            return 'PRIMARY KEY (({0}){1})'.format (', '.join (partition), ((', ' + ', '.join (clustering)) if clustering else '')) 
raise CQLEngineException ('Model {0} PRIMARY KEY composition does not match existing table {1}. Model: {2}.
Table: {3}. Update model or drop the table.'.format (model_clustering, model.column_family_name (), _pk_string (model_partition, model_clustering), _pk_string (meta_partition, meta_clustering))) 

    
    

    Fix the buggy line: raise CQLEngineException ('Model {0} PRIMARY KEY composition does not match existing table {1}. Model: {2}.
Table: {3}. Update model or drop the table.'.format (model_clustering, model.column_family_name (), _pk_string (model_partition, model_clustering), _pk_string (meta_partition, meta_clustering)))
assistant
#Here is Python code to fix the buggy line: raise CQLEngineException ('Model {0} PRIMARY KEY composition does not match existing table {1}.

raise CQLEngineException ('Model {0} PRIMARY KEY composition does not match existing table {1}. Model: {2}; Table: {3}. Update model or drop the table.'.format (model, model.column_family_name (), _pk_string (model_partition, model_clustering), _pk_string (meta_partition, meta_clustering)))