def shuffle(seed=nil)
      seed ||= Random.new_seed

      new_rdd_from_command(Spark::Command::Shuffle, seed)
    end
def shuffle(seed=nil)
      seed ||= Random.new_seed

      new_rdd_from_command(Spark::Command::Shuffle, seed)
    end
Return a shuffled RDD.

 == Example:
   rdd = $sc.parallelize(0..10)
   rdd.shuffle.collect
   # => [3, 10, 6, 7, 8, 0, 4, 2, 9, 1, 5]