1. Introduction

2. Adding an Element to a Hash

3. Testing for the Presence of a Key in a Hash

4. Deleting from a Hash

5. Traversing a Hash

6. Printing a Hash

7. Retrieving from a Hash in Insertion Order

8. Hashes with Multiple Values Per Key

9. Inverting a Hash

10. Sorting a Hash

11. Merging Hashes

12. Finding Common or Different Keys in Two Hashes

13. Presizing a Hash

14. Finding the Most Common Anything

15. Representing Relationships Between Data

16. Program: dutree