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

doc_dir 

        # Gem::Specification.doc_dir

(from ruby core)
### Implementation from Specification
---
    doc_dir(type = nil)

---

Returns the full path to this spec's documentation directory.  If `type`
is given it will be appended to the end.  For example:

    spec.doc_dir      # => "/path/to/gem_repo/doc/a-1"

    spec.doc_dir 'ri' # => "/path/to/gem_repo/doc/a-1/ri"

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.