syntax_data: {"ast_node_type":"variable","tokens":[{"end":42,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let dummy_spans_for_default_args =
context_before:             .map(|arg| arg.span());
context_after:             impl_.of_trait.into_iter().flat_map(|trait_ref| iter::repeat(trait_ref.path.span));