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

sub 

        # Rake::FileList.sub

(from gem rake-13.0.6)
### Implementation from FileList
---
    sub(pat, rep)

---

Return a new FileList with the results of running `sub` against each
element of the original list.

Example:
    FileList['a.c', 'b.c'].sub(/\.c$/, '.o')  => ['a.o', 'b.o']

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.