Give the following sample code, write the following programs: • An iterator class called Iteratefirstn that implements __iter__() and __next__() methods where next method should raise an exception for the cur index if it is passed the last element otherwise set cur index to the next index and advance the index by one, i. e. cur, num = num, num+1. Instantiate the class to calculate sum of 1000000 elements similar to the example. • Instead of implementing the class, write a generator function that does the same thing.