in src/main/scala/com/spotify/bdrc/pipeline/CountUsers.scala [71:77]
def sparkWithAlgebird(input: RDD[Rating]): Long = {
import com.twitter.algebird.Aggregator.count
import com.twitter.algebird.spark._
input.algebird
// `aggregate` is an action and collects data back to the driver node
.aggregate(count(_.user == "Smith"))
}