//fits better in the lenguage
public static Expense Produce(ProducerId producerId, DateTime occurred, Money cost, CategoryId categoryId)
{
Guard.ThrowIfItIsNull(producerId, nameof(producerId));
Guard.ThrowIfItIsNull(occurred, nameof(occurred));
Guard.ThrowIfItIsNull(cost, nameof(cost));
Guard.ThrowIfItIsNull(categoryId, nameof(categoryId));
return(new Expense(producerId, occurred, cost, categoryId));
}
public Producer(ProducerId identifier)
{
Identifier = identifier;
}