syntax_data: {"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// visible. Universes are arranged into a tree: the root universe
context_before:     /// presence of `for<..>` binders to control what sets of names are
context_after:     /// contains names that are always visible. Each child then adds a new