C# how to use iterator

//  create iterator method 

      public IEnumerable<decimal?> BucketIterator(Accounts_basic a ) {
            int cycle = 0;
            for (int i=7 ; i > 0 ; i--){

                    switch (i) {
                 case 1:yield return a.dd_15;break;

                         case 2 :yield return a.dd_30; break;

                         case 3:yield return a.dd_60; break;

                         case 4:yield return a.dd_90; break;

                         case 5 :yield return a.dd_120; break;

                         case 6:yield return a.dd_150; break;

                         case 7:yield return a.dd_180; break;

                 default : yield break;

                }

            }

// use iterator method as follows
 foreach (decimal? amount in BucketIterator(accounts_basic)) {
        // use amount here 
}