syntax_data: {"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let mut pred_count = IndexVec::from_elem(0u8, &body.basic_blocks);
context_before:     fn run_pass(&self, _tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
context_after:         for (_, data) in body.basic_blocks.iter_enumerated() {