syntax_data: {"ast_node_type":"other","tokens":[{"end":73,"kind":"keyword","start":0,"text":"ty::Contravariant"}]}
source_snippet:             ty::Contravariant => self.infcx.sub_regions(a, b, self.span),
context_before:             // Suptype(&'a u8, &'b u8) => Outlives('b: 'a) => SubRegion('a, 'b)
context_after:             ty::Invariant => self.infcx.equate_regions(a, b, self.span),