Create a public class named MyString. MyString should provide a public constructor that accepts a single String argument and rejects null Strings. Your string variable should be private.

MyString should also implement the Comparable interface. Normally Strings are compared lexicographically: "aaa" comes before "z". MyString should compare instances based on the length of its stored String. So MyString("aaa") should come after MyString("z"), since "aaa" is longer than "z". Note that you should implement Comparable<MyString>, meaning that MyString instances can be compared with other MyString instances but not with other objects. As a result, the signature of compareTo will be fun compareTo(other: MyString): Int, accepting a MyString rather than an Any.

You will probably need to review the documentation for Comparable.