syntax_data: {"ast_node_type":"other","tokens":[{"end":50,"kind":"keyword","start":0,"text":"impl_obligations.extend(args.obligations);"}]}
source_snippet:         impl_obligations.extend(args.obligations);
context_before:         // e.g., `impl<U: Tr, V: Iterator<Item=U>> Foo<<U as Tr>::T> for V`