syntax_data: {"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// This is `None` after we finish encoding `SyntaxContexts`, to ensure
context_before:     /// All `SyntaxContexts` for which we have written `SyntaxContextData` into crate metadata.
context_after:     /// that we don't accidentally try to encode any more `SyntaxContexts`