Dataclusters iter() not functioning in PeakExtraction class

[stevenhua0320]

When running peakextraction.py example, we have this error
Traceback (most recent call last):
File "/Users/huarundong/dbs/diffpy.srmise/diffpy.srmise/src/diffpy/srmise/peakextraction.py", line 1331, in <module> te.extract_single()
File "/Users/huarundong/dbs/diffpy.srmise/diffpy.srmise/src/diffpy/srmise/peakextraction.py", line 796, in extract_single for step in dclusters:
TypeError: iter() returned non-iterator of type 'DataClusters'
It still maintains the DataClusters original __iter__ and I changed original next() to __next__, but the issue persists.