syntax_data: {"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let success_block = this.cfg.start_new_block();
context_before:                 // might contain statements that we don't want on the LHS path.)
context_after:                 this.cfg.goto(lhs_success_block, args.variable_source_info, success_block);