/// <summary>
  /// Creates a monthly subscription request.
  /// </summary>
  /// <param name="email">The email.</param>
  /// <param name="subscriptionName">Name of the subscription.</param>
  /// <param name="amount">The amount.</param>
  /// <param name="numberOfBillings">The number of billings. So if you wanted to create a monthly subscription that lasts for a year - this would be 12</param>
  /// <returns></returns>
 public static SubscriptionRequest CreateMonthly(string email, string subscriptionName, decimal amount, short numberOfBillings) {
      var sub = new SubscriptionRequest();
      sub.CustomerEmail = email;
      sub.Amount = amount;
      sub.SubscriptionName = subscriptionName;
      sub.BillingCycles = numberOfBillings;
      return sub;
  }
       /// <summary>
       /// Creates a weekly subscription that bills every 7 days. 
       /// </summary>
       /// <param name="email">The email.</param>
       /// <param name="subscriptionName">Name of the subscription.</param>
       /// <param name="amount">The amount.</param>
       /// <param name="numberOfBillings">The number of billings. If you want this subscription to last for a month, this should be set to 4</param>
       /// <returns></returns>
       public static SubscriptionRequest CreateWeekly(string email, string subscriptionName, decimal amount, short numberOfBillings) {
            var sub = new SubscriptionRequest();
            sub.CustomerEmail = email;
            sub.Amount = amount;
            
            sub.SubscriptionName = subscriptionName;
            sub.BillingCycles = numberOfBillings;           

            sub.BillingIntervalUnits = BillingIntervalUnits.Days;
            sub.BillingInterval = 7;

            return sub;
        }