var model = function() {
  var erp1 = Enumerate(function() {return flip(.4);});
  var erp2 = Enumerate(function() {return flip(.8);});
  var erpX = multiplexERP([true, false], [erp1, erp2]);
  var toss = flip(.5);
  return sample(erpX, [toss]);
}

Enumerate(model);