syntax_data: {"ast_node_type":"variable","tokens":[{"end":41,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let layout: Tree<Def, !, !> =
context_before:         fn visible_def_in_seq_len_2() {
context_after:                 Tree::def(Def::NoSafetyInvariants).then(Tree::def(Def::NoSafetyInvariants));