syntax_data: {"ast_node_type":"function","tokens":[{"end":81,"kind":"keyword","start":0,"text":"pub"}]}
source_snippet:     pub fn is_valid_span(&self, sp: Span) -> Result<(Loc, Loc), SpanLinesError> {
context_before:     #[instrument(skip(self), level = "trace")]
context_after:         let lo = self.lookup_char_pos(sp.lo());