Sample usage of flatMap to create a list of only results from values found in a Map ... More details at: http://sdanzig.blogspot.com/2013/06/the-option-design-pattern.html

flatMap demonstration on the values from a List of keys queried from a Map.scala

  Console.println("\nLast names for list of first names:")
  Console.println(List("beth","sam","harry").flatMap(
    firstToLastNameMap.get(_)).map("["+_+"]").mkString(","))
    
/*
Output:

Last names for list of first names:
[peterson],[smith]
*/