syntax_data: {"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let src = Tree::Def(Def::NoSafetyInvariants).then(Tree::u8());
context_before:     fn src_safe_dst_safe() {
context_after:         let dst = Tree::Def(Def::NoSafetyInvariants).then(Tree::u8());