This is a Ruby tree! It shows every object from the Ruby Programming Language in a tree format.

- 

        # Set.-

(from ruby core)
---
    -(enum)

---

Returns a new set built by duplicating the set, removing every
element that appears in the given enumerable object.
    Set[1, 3, 5] - Set[1, 5]                #=> #<Set: {3}>
    Set['a', 'b', 'z'] - ['a', 'c']         #=> #<Set: {"b", "z"}>

This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.