syntax_data: {"ast_node_type":"other","tokens":[{"end":35,"kind":"keyword","start":0,"text":"metavar_spans:"}]}
source_snippet:     metavar_spans: MetavarSpansMap,
context_before:     /// Collisions are possible and processed in `maybe_use_metavar_location` on best effort basis.
context_after:     hygiene_data: Lock<hygiene::HygieneData>,