error: value toDS is not a member of Seq[Int] SQL

[shengshanzhang]

Hi,

        On spark website, there is code as follows showing how to create 
datasets.
 

        However when i input this line into spark-shell,there comes a Error, 
and who can tell me Why and how to fix this?

scala> val ds = Seq(1, 2, 3).toDS()
<console>:35: error: value toDS is not a member of Seq[Int]
       val ds = Seq(1, 2, 3).toDS()



        Thank you a lot!