ppr_co p co@(TcTyConAppCo _ tc [_,_])
  | tc `hasKey` funTyConKey = ppr_fun_co p co
ppr_co p co@(TcTyConAppCo _ tc [_,_])
  | tc `hasKey` funTyConKey = ppr_fun_co p co
ppr_co p co@(TcTyConAppCo _ tc [_,_])
  | tc `hasKey` funTyConKey = ppr_fun_co p co