Erase the unsed function
Merge branch 'master' of https://github.com/earthreader/libearth
Remove useless print codes
Stage subscriptions test
Merge branch 'master' of https://github.com/earthreader/libearth
Change categories to dictionary to access Category instance
import reduce on python 3.x
Make iter(SubscriptionSet) to return unique set
write() can explicitly return chunk as bytes
Person is now hashable