syntax_data: {"ast_node_type":"other","tokens":[{"end":20,"kind":"keyword","start":0,"text":"match"}]}
source_snippet:         match file {
context_before:     fn map_filename_prefix(&self, file: &FileName) -> (FileName, bool) {
context_after:             FileName::Real(realfile) if let RealFileName::LocalPath(local_path) = realfile => {