# File lib/heckle.rb, line 575
  def mutations_left
    @last_mutations_left ||= -1

    sum = 0
    @mutatees.each { |mut| sum += mut.last.size }

    if sum == @last_mutations_left then
      puts 'bug!'
      puts
      require 'pp'
      puts 'mutatees:'
      pp @mutatees
      puts
      puts 'original tree:'
      pp @original_tree
      puts
      puts "Infinite loop detected!"
      puts "Please save this output to an attachment and submit a ticket here:"
      puts "http://rubyforge.org/tracker/?func=add&group_id=1513&atid=5921"
      exit 1
    else
      @last_mutations_left = sum
    end

    sum
  end