Problem with join in__str__() in class (newbie)

[MRAB]

Fencer wrote:
> jon rascal wrote:
>>
>> You're turning your list into a string -- try this:
>> ', '.join([str(x) for x in self.topics])
> 
> Thanks for your quick reply, unfortunately it didn't quite work for me.
> Say topics contain two topics: polemics, and the parthenon I get this 
> output:
> e2:Carla
> Known topics: t5:Polemics
> 
> only the first topic is printed. If topics only contain a single topic I 
> get this error:
> Traceback (most recent call last):
>   File "C:\Users\fencer\workspace\Find Expert\src\find_expert.py", line 
> 57, in <module>
>     print experts[1]
>   File "C:\Users\fencer\workspace\Find Expert\src\find_expert.py", line 
> 21, in __str__
>     output += '\nKnown topics: %s' % (', '.join([str(x) for x in 
> self.topics]))
> TypeError: iteration over non-sequence
> 
> What did I do wrong?
> 
Try printing self.topics. It should always be a list of topics.