code: def _countOverlapIndices(self, i, j):
      
      if self.bucketMap.has_key(i) and self.bucketMap.has_key(j):
        iRep = self.bucketMap[i]
        jRep = self.bucketMap[j]
        return self._countOverlap(iRep, jRep)
      else:
        raise ValueError("Either i or j don't exist")
docs: Return the overlap between bucket indices i and j