syntax_data: {"ast_node_type":"other","tokens":[{"end":81,"kind":"keyword","start":0,"text":"//"}]}
source_snippet: // if we haven't already seen the id of the `SyntaxContext` we are deserializing.
context_before: // The provided closure will be invoked to deserialize a `SyntaxContextData`
context_after: pub fn decode_syntax_context<D: Decoder>(