Support for k-ary tries

[pnowosie]

Number of children suggest that we could build k-ary tries (k > 2). However proofs can only work for the binary tries (2 children)

Do you think it makes sense to support k-ary merkle tries. Otherwise we can simplify the code :)

BTW: proof support for k-ary tries should be fun to implement :nerd_face:

[yosriady]

Looking at the crypto space, Merkle trees typically use a branching factor of 2. I think we can simplify the code. Feel free to send in a PR!

I can't think of a use case for k-ary merkle tries. If there are some pressing use cases, the k-ary proof support would be useful. 🙂