syntax_data: {"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:         if let Ok(prev_source) = self.span_to_prev_source(sp) {
context_before:     pub fn span_extend_to_prev_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
context_after:             let prev_source = prev_source.rsplit(c).next().unwrap_or("");