syntax_data: {"ast_node_type":"other","tokens":[{"end":95,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
context_before: pub struct HygieneEncodeContext {
context_after:     /// This is `None` after we finish encoding `SyntaxContexts`, to ensure