Design a class called Sentence that has a constructor that takes a string representing the sentence as input. The class should have the following methods: get_first_word): returns the first word as a string get al_wordsl): returns all words in a list. replacelindex, new_word) Changes a word at a particular index to "new_word". For example, if sentences is "I'm going back", then replace[2, "home"] results in "l'm going home". If the index is not valid, the method does not do anything.