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

captures 

        # StringScanner.captures

(from ruby core)
---
    captures

---

Returns the subgroups in the most recent match (not including the full
match). If nothing was priorly matched, it returns nil.

    s = StringScanner.new("Fri Dec 12 1975 14:39")
    s.scan(/(\w+) (\w+) (\d+) /)       # -> "Fri Dec 12 "
    s.captures                         # -> ["Fri", "Dec", "12"]
    s.scan(/(\w+) (\w+) (\d+) /)       # -> nil
    s.captures                         # -> nil

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.