public bool CanAddLoan(Loan loan)
{
//Need unique because this is how the manager ids loans in sending the payments back.
return !currentLoans.ContainsKey(loan.GetName());
}
public void AddLoan(Loan newLoan)
{
if (CanAddLoan(newLoan)) currentLoans.Add(newLoan.GetName(), newLoan);
else throw new InvalidOperationException("There is already a loan issued with this name.");
}