syntax_data: {"ast_node_type":"other","tokens":[{"end":63,"kind":"keyword","start":0,"text":"self.span_to_source(sp,"}]}
source_snippet:         self.span_to_source(sp, |src, start_index, end_index| {
context_before:     pub fn span_to_snippet(&self, sp: Span) -> Result<String, SpanSnippetError> {
context_after:             src.get(start_index..end_index)