syntax_data: {"ast_node_type":"other","tokens":[{"end":31,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:     // this is done on the fly.
context_before:     // so we convert the directed graph into a tree by skipping all previously visited nodes using a visited set.
context_after:     // Each loop run emits a slice - it starts by find a "childless" unvisited node, backtracking upwards, and it