syntax_data: {"ast_node_type":"other","tokens":[{"end":34,"kind":"keyword","start":0,"text":"f.debug_struct(\"Span\")"}]}
source_snippet:             f.debug_struct("Span")
context_before:         fn fallback(span: Span, f: &mut fmt::Formatter<'_>) -> fmt::Result {
context_after:                 .field("lo", &span.lo())