syntax_data: {"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:             // Check if `exists<..> A == for<..> B`
context_before:             // `exists<..> A == for<..> B` and `exists<..> B == for<..> A`.
context_after:             ty::Invariant => {