syntax_data: {"ast_node_type":"variable","tokens":[{"end":44,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let block = BasicBlockData::new(
context_before:         let mut new_block = |source_info: SourceInfo, is_cleanup: bool, target: BasicBlock| {
context_after:                 Some(Terminator { source_info, kind: TerminatorKind::Goto { target } }),