Functional programming in Scala problem:

Output the pairs of consecutive words that occur in the text most often. By pairs of consecutive words we are referring to two words that occur one after the other in the text. For example (output, the), (the, pairs), (pairs, of), and so on. For the purpose of this algorithm we ignore the case of characters in the words (and any punctuation). For example: The pairs of words that occur most often are [(in, the), (over, and)]. Each of these pairs of words occurs 8 times in the text.