syntax_data: {"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // StorageLive(_4);        // _4 is `x`
context_before:             // ```
context_after:             // _4 = &mut (_1.0: i32);  // this is handling `(mut x, 1)` case