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

% 

        # String.%

(from ruby core)
---
    string % object -> new_string

---

Returns the result of formatting `object` into the format specification
`self` (see Kernel#sprintf for formatting details):

    "%05d" % 123 # => "00123"

If `self` contains multiple substitutions, `object` must be an Array or
Hash containing the values to be substituted:

    "%-5s: %016x" % [ "ID", self.object_id ] # => "ID   : 00002b054ec93168"
    "foo = %{foo}" % {foo: 'bar'} # => "foo = bar"
    "foo = %{foo}, baz = %{baz}" % {foo: 'bar', baz: 'bat'} # => "foo = bar, baz = bat"

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.