syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"///"}]}
source_snippet: /// sent to other threads, but some pieces of performance infra run in a separate thread.
context_before: /// `SpanData` is public because `Span` uses a thread-local interner and can't be
context_after: /// Using `Span` is generally preferred.