Create a new class called Sentence.

• The constructor should accept a single parameter that is a string. Create an instance variable that stores the sentence as a string. Assume the sentence has no punctuation.
• Write accessor method getSentence: Return the sentence as a string.
• Write accessor method getWords: Return the list of words in the sentence.
• Write accessor method getNumWords: Return the number of words in the sentence.
• Write a mutator method for the Sentence class that allows you to capitalize all the words in a sentence.
• Write a mutator method for the Sentence class that allows you to add a punctuation mark to the end of the sentence.
• Add a str  method to the Sentence class
• Implement the getitem method for the Sentence class. This method should allow you to use the index operator notation to access a word in the sentence.
• Implement the len method so that you can use the len operator.
• Implement the contains method so that you can ask if a word is in a sentence.
• Implement the getslice method to allow you to retrieve portions of the sentence. The getslice method should return a Sentence consisting of the words indicated by the slice. For example, if the original sentence was a = Sentence ("the quick brown fox"), then a[1:3] should return the sentence consisting of the words "quick brown".
• Implement the add method to allow you to concatenate two sentences together. Make sure your add method returns a new instance of Sentence.
• Implement the frequencyTable  method that determine the word frequency of a sentence using a dictionary and print a frequency table
• Write a function that tests all the above functions.