text: function toRoman(number) {
    if ((number < 0) || (number > 3999)) {
      throw new Error("insert value betwheen 1 and 3999");
    }
    if (number < 1) return "";
    if (number >= 1000) return "M" + toRoman(number - 1000);
    if (number >= 900) return "CM" + toRoman(number - 900); //EDIT: i've typed 400 instead 900
    if (number >= 500) return "D" + toRoman(number - 500);
    if (number >= 400) return "CD" + toRoman(number - 400);
    if (number >= 100) return "C" + toRoman(number - 100);
    if (number >= 90) return "XC" + toRoman(number - 90);
    if (number >= 50) return "L" + toRoman(number - 50);
    if (number >= 40) return "XL" + toRoman(number - 40);
    if (number >= 10) return "X" + toRoman(number - 10);
    if (number >= 9) return "IX" + toRoman(number - 9);
    if (number >= 5) return "V" + toRoman(number - 5);
    if (number >= 4) return "IV" + toRoman(number - 4);
    if (number >= 1) return "I" + toRoman(number - 1);
    throw new Error("something bad happened");
  }
  
  module.exports = function (number) {
    return toRoman(number);
  };