syntax_data: {"ast_node_type":"variable","tokens":[{"end":53,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let mut prev = (0..=b.len()).collect::<Vec<_>>();
context_before:     let mut prev_prev = vec![usize::MAX; b.len() + 1];
context_after:     let mut current = vec![0; b.len() + 1];