syntax_data: {"ast_node_type":"import","tokens":[{"end":82,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // regions. We use two `DebruijnIndex`es (one for the currently folded
context_before:             // Closure used in `RegionFolder` to create names for anonymous late-bound
context_after:             // late-bound region and the other for the binder level) to determine