syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// is only valid until the result of one of its cycle heads changes.
context_before:     /// global cache and track them locally instead. A provisional cache entry
context_after:     provisional_cache: HashMap<X::Input, Vec<ProvisionalCacheEntry<X>>>,