typing: create custom type, protocol, etc.. that would fit better our classes

[lucashervier]

[fel-thomas]

That's exactly why I put type into it's own module. I have nevertheless a reluctance on the fact that the documentation can be less clear (what is a protocol for a user who does not know the lib)

[lucashervier]

It is a good point, but then we have to make sure the type we use are necessary AND sufficient. Because, it is nice that a user can understand the documentation but it is even better if it allows him to do what he wants!