syntax_data: {"ast_node_type":"variable","tokens":[{"end":59,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let region_scope = (region_scope, source_info);
context_before:             let source_info = this.source_info(expr.span);
context_after:             return this.in_scope(region_scope, lint_level, |this| {