Show the ancestor classes of an object

ancestors.rb

module TryItOut
  class << self
    def ancestors(o)
      a = []
      a << ((o.class == Class) ? o : o.class)
      loop {
        break if a[-1].nil?
        a << a[-1].superclass
      }
      a
    end
  end
end
h = TryItOut.ancestors(File)
puts h.to_s
# TryItOut.ancestors(:a) #=> [Symbol, Object, BasicObject, nil]
# TryItOut.ancestors('') #=> [String, Object, BasicObject, nil]
# TryItOut.ancestors(String) #=> [String, Object, BasicObject, nil]
# TryItOut.ancestors(99) #=> [Fixnum, Integer, Numeric, Object, BasicObject, nil]
# TryItOut.ancestors(File) #=> [File, IO, Object, BasicObject, nil]