human
Solve the following python programming problem given the following code:
def get_select(self, columns = None, with_joins = True) : 
    all_columns = [] 
    column_map = { 
        
} 
    joins = [] 
    def join_table(collection, table, key, params, key_path = None) : 
        if (key_path is None) : 
            key_path = [] 
if isinstance (params ['relation'] ['field'], ManyToManyField) : 
            join_many_to_many (collection, table, key, params, key_path) 
else : 
            if isinstance (params ['relation'] ['field'], ForeignKeyField) : 
                join_foreign_key (collection, table, key, params, key_path) 
else : 
                if isinstance (params ['relation'] ['field'], OneToManyField) : 
                    join_one_to_many (collection, table, key, params, key_path) 
else : 
                    raise AttributeError 
def process_fields_and_subkeys(related_collection, related_table, params, key_path) : 
        params ['table_fields'] = { 
            
} 
        for (field, column_name) in params ['fields'].items () : 
            column_label = '_'.join ((key_path + [column_name])) 
            params ['table_fields'] [field] = column_label 
            try : 
                column = related_table.c [column_name].label (column_label) 
except KeyError : 
                continue 
all_columns.append (column) 
            if (field != '__data__') : 
                column_map ['.'.join ((key_path + [field]))] = column 
for (subkey, subparams) in sorted (params ['joins'].items (), key = (lambda i : i [0])) : 
            join_table (params ['collection'], related_table, subkey, subparams, key_path = (key_path + [subkey])) 
def join_one_to_many(collection, table, key, params, key_path) : 
        related_table = params ['table'].alias () 
        related_collection = params ['relation'] ['collection'] 
        condition = (table.c ['pk'] == related_table.c [params ['relation'] ['backref'] ['column']]) 
        joins.append ((related_table, condition)) 
        process_fields_and_subkeys (related_collection, related_table, params, key_path) 
def...

    
    

    Fix the buggy line: for only_key in direction :
assistant
#Here is Python program to fix the buggy line: for only_key in direction :
.

for only_key in only :