syntax_data: {"ast_node_type":"other","tokens":[{"end":74,"kind":"keyword","start":0,"text":"assert!(len"}]}
source_snippet:                 assert!(len >= prefix.len() as u64 + suffix.len() as u64);
context_before:                     .expect("expected len of array pat to be definite");
context_after:                 PatKind::Array { prefix, slice, suffix }