Find the most common word
Level: Intermediate (score: 3)
Write a function that returns the most common (non stop)word in this Harry Potter text.
Make sure you convert to lowercase, strip out non-alphanumeric characters and stopwords. Your function should return a tuple of (most_common_word, frequency).
The template code already loads the Harry Potter text and list of stopwords in.
Check the tests for more info - have fun!