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

to_a 

        # Set.to_a

(from ruby core)
---
    to_a()

---

Converts the set to an array. The order of elements is uncertain.
    Set[1, 2].to_a                    #=> [1, 2]
    Set[1, 'c', :s].to_a              #=> [1, "c", :s]

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.