syntax_data: {"ast_node_type":"other","tokens":[{"end":89,"kind":"keyword","start":0,"text":"ImplSource::Builtin(BuiltinImplSource::Misc,"}]}
source_snippet:                 ImplSource::Builtin(BuiltinImplSource::Misc, PredicateObligations::new())
context_before:                 // no additional obligations to prove and no types in particular to unify, etc.
context_after:             }