each_slice without block in ruby 1.8.6

if RUBY_VERSION < "1.8.7"
  require 'enumerator'
  module Enumerable
    alias_method :original_each_slice, :each_slice
    def each_slice(count, &block)
      if block_given?
        # call original method when used with block
        original_each_slice(count, &block)
      else
        # no block -> emulate
        self.enum_for(:original_each_slice, count)
      end
    end
  end
end