syntax_data: {"ast_node_type":"other","tokens":[{"end":99,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// - umbrella features: for example if clang accumulates more features in the future than just
context_before:     ///   we can have a single `+target` feature.
context_after:     ///   the `+target` above. That could be modeled as `+clang`.