human
Solve the following python programming problem given the following code:
@ register.filter 
def sort_by(items, attr) : 
    '
    General sort filter - sorts by either attribute or key.
    ' 
    def key_func(item) : 
        try : 
            return getattr (item, attr) 
except AttributeError : 
            try : 
                return item [attr] 
except TypeError : 
                getattr (item, attr) 
return sorted (key_func, key = key_func) 

    
    

    Fix the buggy line: return sorted (key_func, key = key_func)
assistant
#Here is Python code to fix the buggy line: return sorted (key_func, key = key_func)
.

return sorted (items, key = key_func)