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

<< 

        # Method.<<

(from ruby core)
---
    meth << g -> a_proc

---

Returns a proc that is the composition of this method and the given *g*.
The returned proc takes a variable number of arguments, calls *g* with
them then calls this method with the result.

    def f(x)
      x * x
    end

    f = self.method(:f)
    g = proc {|x| x + x }
    p (f << g).call(2) #=> 16

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.