syntax_data: {"ast_node_type":"other","tokens":[{"end":35,"kind":"keyword","start":0,"text":".map(|arg|"}]}
source_snippet:             .map(|arg| arg.span());
context_before:             .flat_map(|trait_ref| trait_ref.path.segments.last().unwrap().args().args)
context_after:         let dummy_spans_for_default_args =