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

<< 

        # String.<<

(from ruby core)
---
    string << object -> string

---

Concatenates `object` to `self` and returns `self`:

    s = 'foo'
    s << 'bar' # => "foobar"
    s          # => "foobar"

If `object` is an Integer, the value is considered a codepoint and
converted to a character before concatenation:

    s = 'foo'
    s << 33 # => "foo!"

Related: String#concat, which takes multiple arguments.

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.