Set inclusion

[Serge D. Mechveliani]

I have the two notes on the GHC library. 
The docs show that 
1. Map has the function for the Map inclusion relation, 
   and Set does not have such for sets.
2. notMember  looks unnecessary, because one can write  
   not . Map.member k.

Regards,
-----------------
Serge Mechveliani
mechvel at botik.ru