Cute way to get frequency of items in an enumerable with some bonus methods on the resulting hash.

enumerable.rb

Enumerable.module_eval do
  def frequency
    Hash.new(0).tap do |h|
      each { |v| h[v] += 1 }
      h.define_singleton_method(:highest) { sort_by(&:last).last.first }
      h.define_singleton_method(:lowest) { sort_by(&:last).first.first }
    end
  end
end