input: Write a python function to create a CreditCardAccount object and test its methods.
  assert account.name == "John Doe"
  assert account.card_number == "1234567890123456"
  assert account.balance == 500
  assert account.limit == 1000
  account.add_to_balance(200)
  assert account.balance == 700
  account.subtract_from_balance(100)
  assert account.balance == 600
output: def test_credit_card_account():
      class CreditCardAccount:
          def __init__(self, name, card_number, balance, limit):
              self.name = name
              self.card_number = card_number
              self.balance = balance
              self.limit = limit
  
          def add_to_balance(self, amount):
              if self.balance + amount <= self.limit:
                  self.balance += amount
  
          def subtract_from_balance(self, amount):
              if self.balance - amount >= 0:
                  self.balance -= amount
  
      account = CreditCardAccount("John Doe", "1234567890123456", 500, 1000)
      assert account.name == "John Doe"
      assert account.card_number == "1234567890123456"
      assert account.balance == 500
      assert account.limit == 1000
      account.add_to_balance(200)
      assert account.balance == 700
      account.subtract_from_balance(100)
      assert account.balance == 600