syntax_data: {"ast_node_type":"other","tokens":[{"end":18,"kind":"keyword","start":0,"text":"_"}]}
source_snippet:             _ => {
context_before:             // `x..y` where `x >= y`, or `x..=y` where `x > y`. The range is empty => error.
context_after:                 // Emit a more appropriate message if there was overflow.