syntax_data: {"ast_node_type":"other","tokens":[{"end":91,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// The `SyntaxContexts` that we have serialized (e.g. as a result of encoding `Spans`)
context_before:     serialized_ctxts: Lock<FxHashSet<SyntaxContext>>,
context_after:     /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`