syntax_data: {"ast_node_type":"function","tokens":[{"end":71,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn lookup_source_file(&self, pos: BytePos) -> Arc<SourceFile> {
context_before:     /// Return the SourceFile that contains the given `BytePos`
context_after:         let idx = self.lookup_source_file_idx(pos);