# File lib/cri/command_dsl.rb, line 191
    def add_option(short, long, desc, argument, block)
      if short.nil? && long.nil?
        raise ArgumentError, "short and long options cannot both be nil"
      end

      @command.option_definitions << {
        :short    => short.nil? ? nil : short.to_s,
        :long     => long.nil? ? nil : long.to_s,
        :desc     => desc,
        :argument => argument,
        :block    => block }
    end