code: def _subtract_range(self, r, partition_key_range):
          
          
          left = max(partition_key_range[routing_range._PartitionKeyRange.MaxExclusive], r.min)
  
          if left == r.min:
              leftInclusive = r.isMinInclusive
          else:
              leftInclusive = False
  
          queryRange = routing_range._Range(left, r.max, leftInclusive,
                  r.isMaxInclusive)
          return queryRange
docs: Evaluates and returns r - partition_key_range
          :param dict partition_key_range:
              Partition key range.
          :param routing_range._Range r: query range.
          :return:
              The subtract r - partition_key_range.
          :rtype: routing_range._Range