syntax_data: {"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"Some(DesugaringKind::WhileLoop)"}]}
source_snippet:                     Some(DesugaringKind::WhileLoop) => LetSource::WhileLet,
context_before:                 let let_source = match ex.span.desugaring_kind() {
context_after:                     _ => match self.let_source {