syntax_data: {"ast_node_type":"other","tokens":[{"end":48,"kind":"keyword","start":0,"text":"self.infcx.enter_forall(a,"}]}
source_snippet:                 self.infcx.enter_forall(a, |a| {
context_before:                 // Check if `exists<..> B == for<..> A`.
context_after:                     let b = self.infcx.instantiate_binder_with_infer(b);