This is a catchy tune I first heard on a wonderful Celtic cello recording by Abby Newton (if you don't know her work, check her out. You're in for a treat!) The tune is so unusual, as it shifts from one mode to the next, so you get to experience the different flavor of Mixolydian, Dorian and Ionian (Major). The result is a playfulness and joy that you have to experience for yourself.
Here's a software-generated mp3 to give you a rough idea:
The lever changes are really not hard, so don't be afraid of them. Just treat a lever change like a note, timing the hand motion on exactly the same beat each time, and you'll find it easy to incorporate that way.
Please download and enjoy Sister Jean!