{"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"RegionNameSource::SynthesizedFreeEnvRegion(span,"}]}
            RegionNameSource::SynthesizedFreeEnvRegion(span, note) => {
            }
                diag.span_label(*span, format!("lifetime `{self}` represents this closure's body"));