Nicolas Dumazet ha scritto:

> A small note here: set is not really meant to be used on incremental
> .add(), because sets are frozen (not mutable), and add() instantiates
> a new set on each .add() action. Sets are useful for set operations
> (union, intersection), but are not really helpful when it comes to
> incrementally construct them. When I need performance for such kind of
> lookups, a simple dictionary is usually way faster than sets :) I
> would suggest using a dictionary here :)

'set' is implemented as a 'dict', using add() method you just are adding
a new keyword, so using directly a 'dict' should be theorically faster.
Unfortunately, I cannot see this in a test I have executed (1,23%
slower). I'll try to run it again later. Maybe I miss something.