first – returns the first element of the RDD (typically a file header)
take – returns a given number of records (like *nix HEAD)
collect – returns the whole dataset
Actions, by default, return results to the local process. The saveAsTextFile actions saves the contents of an RDD to persistent storage, such as HDFS
-This action creates a directory & writes out each partition as a file within it.
foreach println – prints out each value in the array on its own line
foreach printlin is an example of functional programming, where one function (foreach) is passed as an argument to another function (println)