new_contents: from HLL.hyperloglog import BaseHyperLogLog
  from abc import abstractmethod
  
  class BaseKEstimater(object):
      def __init__(kmin, kmax, hashFunc):
          self.kmin = kmin
          self.kmax = kmax
          self.hashFunc = hashFunc
          self.k = 0
  
      def getK(self):
          return int(self.k)
  
      @abstractmethod
      def train(self, data):
          pass
  
  
subject: add kestimate interface