syntax_data: {"ast_node_type":"function","tokens":[{"end":81,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn span_to_snippet(&self, sp: Span) -> Result<String, SpanSnippetError> {
context_before:     /// Returns the source snippet as `String` corresponding to the given `Span`.
context_after:         self.span_to_source(sp, |src, start_index, end_index| {