syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // The number of extra bytes due to multibyte chars in the `SourceFile`.
context_before:     fn bytepos_to_file_charpos(&self, bpos: RelativeBytePos) -> CharPos {
context_after:         let mut total_extra_bytes = 0;