syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"sm.new_source_file(PathBuf::from(\"example.rs\").into(),"}]}
source_snippet:     sm.new_source_file(PathBuf::from("example.rs").into(), "a…b".to_string());
context_before:     let sm = SourceMap::new(FilePathMapping::empty());