def options_hash_to_string(options)
      result = ''
      options.sort_by { |key, _| OPTION_ORDER.find_index(key) || -1 }.each do |key, value|
        if value
          result += "set #{OptionHandling.option_to_string(key, value)}\n"
        else
          result += "unset #{key}\n"
        end
      end
      result
    end
def options_hash_to_string(options)
      result = ''
      options.sort_by { |key, _| OPTION_ORDER.find_index(key) || -1 }.each do |key, value|
        if value
          result += "set #{OptionHandling.option_to_string(key, value)}\n"
        else
          result += "unset #{key}\n"
        end
      end
      result
    end
Convert given options to gnuplot format.

 For "{ opt1: val1, .. , optN: valN }" it returns
   set opt1 val1
   ..
   set optN valN

 @param ptions [Hash] options to convert
 @return [String] options in Gnuplot format