human
Solve the following python programming problem given the following code:
def fill(obj) : 
    def fillRuleSet(obj) : 
        errorMsg = obj ['errorMsg'] 
        if (errorMsg.find ('${selector}') == (- 1)) : 
            errorMsg = (((errorMsg + ' (from "') + obj ['selector']) + '")') 
else : 
            errorMsg = errorMsg.replace ('${selector}', obj ['selector']) 
return errorMsg 
def fillStyleSheet(obj) : 
        errorMsg = obj ['errorMsg'] 
        if (errorMsg.find ('${file}') == (- 1)) : 
            errorMsg = (((errorMsg + ' (from "') + obj ['file']) + '")') 
else : 
            errorMsg = errorMsg.replace ('${file}', obj ['file']) 
return errorMsg 
def fillRule(obj) : 
        errorMsg = obj ['errorMsg'] 
        if (errorMsg.find ('${selector}') == (- 1)) : 
            errorMsg = (((errorMsg + ' (from "') + obj ['selector']) + '")') 
else : 
            errorMsg = errorMsg.replace ('${selector}', obj ['selector']) 
errorMsg = errorMsg.replace ('${name}', obj ['name']) 
        errorMsg = errorMsg.replace ('${value}', obj ['value']) 
        return errorMsg 
level = obj ['level'] 
    if (level == 'rule') : 
        return fillRule (obj) 
else : 
        if (level == 'ruleset') : 
            return fillRuleSet (fillStyleSheet) 
else : 
            if (level == 'stylesheet') : 
                return fillStyleSheet (obj) 
return obj ['errorMsg'] 

    
    

    Fix the buggy line: return fillRuleSet (fillStyleSheet)
assistant
#Here is Python program to find ('${selector}') == (- 1)) : 
.

return fillRuleSet (obj)