When you need to figure out what methods are defined at which point in the class hierarchy.

object.rb

Object.class_eval do
  def hierarch(n = 1)
    klass_and_ancestry = self.class.ancestors[(n - 1)..-1]
    klass, *ancestry = klass_and_ancestry
    to_klass_methods = methods - ancestry.flat_map(&:instance_methods)
    "#{klass}: #{to_klass_methods}"
  end
end