syntax_data: {"ast_node_type":"other","tokens":[{"end":66,"kind":"keyword","start":0,"text":"///"}]}
source_snippet:     /// Mirrors `Variance::xform` - used to 'combine' the existing
context_before: impl<I: Interner> VarianceDiagInfo<I> {
context_after:     /// and new `VarianceDiagInfo`s when our variance changes.