new_contents: from abc import ABCMeta
  
  class DatasetAdapter(object):
      __metaclass__ = ABCMeta
  
      def __init__(self):
          pass
  
      def createTrace(self):
          pass
  
      def createInstance(self):
          pass
  
      def createType(self);
          pass
  
      def createSet(self):
          pass
  
subject: add dataset adapter class