{"ast_node_type":"other","tokens":[{"end":88,"kind":"keyword","start":0,"text":"//"}]}
// boundary and dropped in the other thread, it would exit the span in the other thread.
// The Phantomdata exists to prevent this type from being `Send`. If it were sent across a thread
struct SpanGuard(tracing::Span, std::marker::PhantomData<*const u8>);