{"ast_node_type":"other","tokens":[{"end":91,"kind":"keyword","start":0,"text":"(Some(len),"}]}
            (Some(len), VarLen(prefix, suffix)) if prefix + suffix == len => FixedLen(len),
            // If the middle `..` has length 0, we effectively have a fixed-length pattern.
            (Some(len), VarLen(prefix, suffix)) if prefix + suffix > len => panic!(