code: def __buildROC(self, values, period, rocMaxLen=None):
      seqDS = dataseries.SequenceDataSeries()
      ret = roc.RateOfChange(seqDS, period, rocMaxLen)
      for value in values:
          seqDS.append(value)
      return ret
  
file_path: pyalgotrade/testcases/technical_roc_test.py
imports: from six.moves import xrange
  from .None import common
  from pyalgotrade.technical import roc
  from pyalgotrade import dataseries
label_desc: Use image node_id 1 for calling the ROCTestCase obj's underlying member method code with example usage: obj.__buildROC(values, period, rocMaxLen) and returns: ret