{"ast_node_type":"other","tokens":[{"end":133,"kind":"keyword","start":0,"text":"//"}]}
// FIXME: Generate proper `index_mut` method body refer to `index` method body may impossible due to the unpredictable case [#15581].
// Here just leave the `index_mut` method body be same as `index` method body, user can modify it manually to meet their need.