text: const add = (x, y) => +x + +y
  const subtract = (x, y) => +x - +y
  const multiply = (x, y) => +x * +y
  const divide = (x, y) => +x / +y
  
  const validateNumbers = (x, y) => {
      if (isNaN(x) || isNaN(y)) {
        return false
      }
      return true
    }
  
  module.exports = {
    add,
    subtract,
    multiply,
    divide,
    validateNumbers
  }