Re: Flow
```
from pywikibot.flow import Board
site = pywikibot.Site('test', 'test')
board = Board(site, 'Talk:Sandbox')
topics_list = page.topics(limit=2, sort_by='newest')
for topic in topics_list:
print(topic)
```
returns the expected output:
```
[[test:Topic:T63mvwp0c7chy9c3]]
[[test:Topic:T5y39gw54bnw2ice]]
[[test:Topic:T40a7hu3rdj1w3kv]]
[[test:Topic:T2d0esp9nk0tvt2z]]
[[test:Topic:T2d0bc2kfgj5z7d2]]
...
```
***
But when `sort_by='updated'` is passed, the following error throws up:
```
======================================================================
ERROR: test_topic (tests.flow_thanks_tests.TestFlowThank)
----------------------------------------------------------------------
Traceback (most recent call last):
File "tests/flow_thanks_tests.py", line 54, in test_topic
for topic in topics_list:
File "pywikibot/flow.py", line 140, in topics
data = self.site.load_topiclist(self, **cont_args)
File "pywikibot/site.py", line 1357, in callee
return fn(self, *args, **kwargs)
File "pywikibot/site.py", line 6455, in load_topiclist
offset = pywikibot.Timestamp.fromtimestampformat(offset)
File "pywikibot/__init__.py", line 178, in fromtimestampformat
return cls.strptime(ts, cls.mediawikiTSFormat)
TypeError: must be string, not list
```