{"ast_node_type":"other","tokens":[{"end":60,"kind":"keyword","start":0,"text":"|"}]}
            | ObligationCauseCode::HostEffectInExpr(..) => {
            traits::ObligationCauseCode::WhereClauseInExpr(_, _, _, _)
                // This is the "root"; we assume that the `expr` is already pointing here.