This is a Ruby tree! It shows every object from the Ruby Programming Language in a tree format.
# Set.difference (from ruby core) --- difference(enum) --- (This method is an alias for Set#-.) Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object. Set[1, 3, 5] - Set[1, 5] #=> #<Set: {3}> Set['a', 'b', 'z'] - ['a', 'c'] #=> #<Set: {"b", "z"}>
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.