text: describe('createCalculator', () => {
  
      it('add number should work', () => {
          let calculator = createCalculator();
          calculator.add(1);
          let expectResult = 1;
          let actualResult = calculator.get();
          expect(actualResult).to.be.equal(expectResult);
      });
      it('substract number should work', () => {
          let calculator = createCalculator();
          calculator.subtract(1);
          let expectResult = -1;
          let actualResult = calculator.get();
          expect(actualResult).to.be.equal(expectResult);
      });
      it('add and substract multiple numbers should work', () => {
          let calculator = createCalculator();
          calculator.add(1);
          calculator.subtract(1);
          calculator.add(2);
          calculator.subtract(5);
          let expectResult = -3;
          let actualResult = calculator.get();
          expect(actualResult).to.be.equal(expectResult);
      });
      it('add and substract multiple numbers and numbers as string should work', () => {
          let calculator = createCalculator();
          calculator.add('1');
          let expectResult = 1;
          let actualResult = calculator.get();
          expect(actualResult).to.be.equal(expectResult);
      });
      it('add and substract multiple numbers and numbers as string should work', () => {
          let calculator = createCalculator();
          calculator.add('a');
          calculator.subtract(1);
          calculator.add('2');
          calculator.subtract(5);
          let actualResult = calculator.get();
          expect(actualResult).to.be.NaN;
      });
      it('should return module', () => {
          let calculator = createCalculator();
          expect(typeof calculator).to.equals('object');
      });
  
  });