syntax_data: {"ast_node_type":"other","tokens":[{"end":52,"kind":"keyword","start":0,"text":"self.span_to_source(span,"}]}
source_snippet:         self.span_to_source(span, |s, start, _end| {
context_before:     ) -> Result<Span, SpanSnippetError> {
context_after:             let n = s[..start]