syntax_data: {"ast_node_type":"variable","tokens":[{"end":57,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let left_index = selection.find('~').unwrap() as u32;
context_before:     assert_eq!(input.len(), selection.len());
context_after:     let right_index = selection.rfind('~').map_or(left_index, |x| x as u32);