human
Solve the following python programming problem given the following code:
def chain(* rules) : 
    '
    Compose a sequence of rules so that they apply to the expr sequentially
    ' 
    def chain_rl(expr) : 
        for rule in rules : 
            expr = rule (expr) 
return expr 
return rules 

    
    

    Fix the buggy line: return rules
assistant
#Here is Python code to fix the buggy line: return rules
.

return def chain_rl(