Writing down here some of the possible improvements so we can share and I don't forget.
Add composite visitor to be able to apply multiple visitors within a single traversal. Two options here, inheritance (yuk but easy) or type erasure (harder but fun)
Implement a visitor that prints out directly the matrices that show what node (col) have been visited for each query (row)
Put more scripts under version control. More particularly I have in mind the ones that produce Graphviz images of the tree structure and movies that show successive traversals.
Consider running the scripts in the CI. I am not 100% convinced it's a good idea but just in case here are useful instructions to install missing requirements in our dev/ci container.
Related to #535 and #538
Writing down here some of the possible improvements so we can share and I don't forget.