gistfile1.rb

class Enumerator
  def end?
    peek
    false
  rescue StopIteration
    true
  end
end

enum = Enumerator.new { |yielder| yielder.yield 1; yielder.yield 2 }
enum.end? # => false
enum.next # => 1
enum.end? # => false
enum.next # => 2
enum.end? # => true