syntax_data: {"ast_node_type":"import","tokens":[{"end":79,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// may cause us to serialize more `SyntaxContext`s, so serialize in a loop
context_before:     /// in the most recent 'round' of serializing. Serializing `SyntaxContextData`
context_after:     /// until we reach a fixed point.