# File lib/action_mailer/vendor/text-format-0.6.3/text/format.rb, line 335
    def hyphenator=(h)
      raise ArgumentError, "#{h.inspect} is not a valid hyphenator." unless h.respond_to?(:hyphenate_to)
      arity = h.method(:hyphenate_to).arity
      raise ArgumentError, "#{h.inspect} must have exactly two or three arguments." unless [2, 3].include?(arity)
      @hyphenator = h
      @hyphenator_arity = arity
    end