void LiftUserDefinedOperators(List<IMethod> operators)
{
int nonLiftedMethodCount = operators.Count;
// Construct lifted operators
for (int i = 0; i < nonLiftedMethodCount; i++) {
var liftedMethod = LiftUserDefinedOperator(operators[i]);
if (liftedMethod != null)
operators.Add(liftedMethod);
}
}