App

class Calc {

  add(a, b) {
    if (typeof a !== 'number' || typeof b !== 'number') {
      throw new TypeError('You entered not a number value for parameters');
    }
    return a + b;
  }

  multiply(a, b) {
    if (typeof a !== 'number' || typeof b !== 'number') {
      throw new TypeError('You entered not a number value for parameters');
    }
    return a * b;
  }
}

module.exports = new Calc();