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

def_module 

        # ERB.def_module

(from ruby core)
---
    def_module(methodname='erb')

---

Create unnamed module, define *methodname* as instance method of it, and
return it.

example:
    filename = 'example.rhtml'   # 'arg1' and 'arg2' are used in example.rhtml
    erb = ERB.new(File.read(filename))
    erb.filename = filename
    MyModule = erb.def_module('render(arg1, arg2)')
    class MyClass
      include MyModule
    end

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.