The code below shows a class DataSet, which provides basic statistical functionality on a set of data, and a class ExamMarks, which uses DataSet to store and work out the average of a set of exam marks. The main function shown reads in two marks and uses ExamMarks to store them and print out the average. Draw a sequence diagram showing the interaction that takes place when the main function executes.

class DataSet private float data private int items public Data Set data new float. [256] items public void addDataPoint (float d) data [items++] d public float mean float total o for (int i o i get Size i++) total data [i] return total get Size public int getsize return items; Class ExamMarks private Dataset marks public void enterMark (float m) if (marks null) marks new Data Set marks addDataPoint (m) float average return marks. mean public class Average public static void main (string args ExamMarks exam new ExamMarks exam enterMark (56) exam enterMark (72) System. out print, ln (exam average