function sortByPrice (validProducts) {
    validProducts.sort(compareValues)
    function convertStringToNumber (num) {
      return parseInt(num)
    }
    function compareValues (a, b) {
      const firstProductPrice = convertStringToNumber(a.product_price)
      const secondProductPrice = convertStringToNumber(b.product_price)
      if (firstProductPrice > secondProductPrice) {
        return -1
      }
      if (firstProductPrice < secondProductPrice) {
        return 1
      }
      return 0
    }
  }