# File lib/htmldiff.rb, line 144
    def add_matching_words_left(match_in_old, match_in_new, match_size, start_in_old, start_in_new)
      while match_in_old > start_in_old and 
            match_in_new > start_in_new and 
            @old_words[match_in_old - 1] == @new_words[match_in_new - 1]
        match_in_old -= 1
        match_in_new -= 1
        match_size += 1
      end
      [match_in_old, match_in_new, match_size]
    end