fromisoformat is new in py 3.7 - so should not be used for clld apps (yet):
File "/home/forkel/venvs/crossgram/crossgram/crossgram/lib/cldf.py", line 375, in load
published = date.fromisoformat(contrib_md['published'])
AttributeError: type object 'datetime.date' has no attribute 'fromisoformat'
fromisoformat
is new in py 3.7 - so should not be used for clld apps (yet):