Pau

This is a quite important improvement. With a few thousands of indexes any operation with that kind of record becomes very very slow. Actually I would say many people around...

> I don't think it could be a problem for the encoded index value to contain a separator character : there, because we'd never need to do anything like strings.Split(indexKey,...

This is not 100% correct... Sometimes the test will fail and I don't know why (yet). Maybe someone with more knowledge on this SMT implementation can find the problem.

So with this last implementation, `go test -timeout 30s . -run ^TestTrieWalk$ -count=1` works always but `-count=10` crashes... I'm not sure if this is something from my changes or just...

I did not know about the existence of that repository, I'll take a look. However, from a SMT API consumer perspective with the experience of using several goLang Merkletree implementations...

Hey @paouvrard I have been out for some days but now I'm back. Thank you for your review, I am going to incorporate the changes.

I applied your suggestions and now `go test -timeout 30s . -run=^TestTrieWalk$ -count=100` works fine, thank you! I added another function named `GetWithRoot` in order to Get a value for...

Damn it, `go test -timeout 30s . -count=100` fails... I'll look into it.

Fixed! Now `go test -timeout 120s . -count=100` works for me.

The last version solves concurrency problems and it is data race safe. Tested with `go test -timeout 120s . -run ^TestTrieWalk$ -count=100 -race`