@erdii can you please code review?
It seems that the changes you made to dependencies in b208726 has messed up the npm install process on old node versions and I'm not sure how to solve it besides force upgrading npm to v3 in those tests

@regevbr yes there are breaking changes in the pipeline. we will be dropping support for node < 6.x (maybe even 6.x) in the next major release.
I should remove those old node versions from the tests... 😅

Code is nice and should work, but the call to exists (to check if the key already expired and was not cleaned up yet) is missing.

PS: CoffeeScript has an existential operator: instead of x != null you can write x?

@erdii thanks! that is a good catch - I fixed the code and added tests to that use case.

About the deprecation, please keep support for node 6 as I'm stuck with it sadly and not in a position to upgrade.

@regevbr Ok I'll bring that up when we'll talk about compatibility! Thanks for your work here!