syntax_data: {"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":"OpaqueTypeStorageLookup"}]}
source_snippet:     OpaqueTypeStorageLookup { result: QueryResult<I> },
context_before:     /// Try to unify an opaque type with an existing key in the storage.
context_after:     /// Checking that a rigid alias is well-formed.