Functional programming in Scala problem:

Output any pairs of words in the text that are the mirror image of each other. For example, if the text contains the word pan, and at any other place the word nap occurs, then this pair of words are mirror images of each other (nap, pan). The output should contain all such pairs of mirror-image words that appear in the text. For example: The following pairs of mirror-image words appear in the text: [(on, no), (nap, pan), (parts, strap)]