syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"_"}]}
source_snippet:                     _ => match self.let_source {
context_before:                     Some(DesugaringKind::WhileLoop) => LetSource::WhileLet,
context_after:                         LetSource::Else => LetSource::ElseIfLet,