#Chapter 1
#Chapter 2
##Lesson 1
##Lesson 2
##Lesson 3
#Chapter 3
##Lesson 1
###Page 1
###Page 2
###Page 3
##Lesson 2
#Requirements:
- If XML tree has only chapter, don't show dropdown.
- If XML tree has chapter with lessons but no pages, don't show dropdown for pages.
- If XML tree has chapters, with lessons having pages, show dropdown for both chapters and pages.