old_contents: 
  customers = 
      {
          'id': 1,
          'first-name': 'fido',
          'last-name': 'hanks'
          'gender': 'male',
          'age': 23,
          'email': 'fido1@gmail.com',
          'address-line1':'10420 Queens Blvd',
          'address-line2':'16-V',
          'phonenumber' : 123456,      
      },
      {
          'id': 2,
          'first-name': 'shirley',
          'last-name': 'yang'
          'gender': 'female',
          'age': 22,
          'email': 'shirley2@gmail.com',
          'address-line1':'8th street Mahaton',
          'address-line2':'302',
          'phonenumber' : 234567,   
      }
  ]
  
  @app.route('/customers', methods=['POST'])
  def create_customers():
      payload = request.get_json()
      if is_valid(payload):
          id = next_index()
          customer = {'id': id, 'first-name': payload['first-name'], 'last-name': payload['last-name'], 'gender': payload['gender'], 'age': payload['age'],'email':payload['email'], 'address-line1': payload['address-line1'], 'address-line2': payload['address-line2'], 'phonenumber': payload['phonenumber']}
          customers.append(customer)
          message = customer
          rc = HTTP_201_CREATED
      else:
          message = { 'error' : 'Data is not valid' }
          rc = HTTP_400_BAD_REQUEST
  
      return make_response(jsonify(message), rc)
new_contents: 
  customers = [
      {
          'id': 1,
          'first-name': 'fido',
          'last-name': 'hanks'
          'gender': 'male',
          'age': 23,
          'email': 'fido1@gmail.com',
          'address-line1':'10420 Queens Blvd',
          'address-line2':'16-V',
          'phonenumber' : 123456,      
      },
      {
          'id': 2,
          'first-name': 'shirley',
          'last-name': 'yang'
          'gender': 'female',
          'age': 22,
          'email': 'shirley2@gmail.com',
          'address-line1':'8th street Mahaton',
          'address-line2':'302',
          'phonenumber' : 234567,   
      }
  ]
  
  @app.route('/customers', methods=['POST'])
  def create_customers():
      payload = request.get_json()
      if is_valid(payload):
          id = next_index()
          customer = {'id': id, 'first-name': payload['first-name'], 'last-name': payload['last-name'], 'gender': payload['gender'], 'age': payload['age'],'email':payload['email'], 'address-line1': payload['address-line1'], 'address-line2': payload['address-line2'], 'phonenumber': payload['phonenumber']}
          customers.append(customer)
          message = customer
          rc = HTTP_201_CREATED
      else:
          message = { 'error' : 'Data is not valid' }
          rc = HTTP_400_BAD_REQUEST
  
      return make_response(jsonify(message), rc)
subject: modify a little