I need the best answer Python

a 1. Write a function unique Words () that takes a list of sentences (strings). You will return a list of unique words found across all the sentences. Case needs to be ignored. The following shows several sample runs of the function: >>> uniqueWords (I'this is a test', 'not too hard a problem', 'could be on a test, 'i like the word test']) ['this', 'is', 'a', 'test', 'not', 'too', 'hard', 'problem', 'could', 'be', on 'i', 'like', 'the', 'word'] >>> uniqueWords (1) >>> uniqueWords (I'Can you see', 'See you can', 'You can see']) ('can', 'you', 'see']