syntax_data: {"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let (var, ..) = self.parse_var(pattern)?;
context_before:             StmtKind::Let { pattern, initializer: Some(initializer), .. } => {
context_after:                 let data = BasicBlockData::new(