Need help on a project To :"Create a class called BankAccount with the following parameters "

[malitician at gmail.com]

you are absolutely correct Mark 
i'm a beginner in python and  from the original question and test case given above i wrote this 



class BankAccount(object):
    def __init__(self, initial_balance=0):
        self.balance = initial_balance
    def deposit(self, amount):
        self.balance +=amount
    def withdraw(self, amount):
        self.balance -= amount
my_account = BankAccount(90)
my_account.withdraw(1000)
if my_account.balance < 4:
    print('invalid transaction')
class MinimumBalanceAccount(BankAccount):
    def __init__(self, MinimumBalance=4):
        self.minbalance = MinimumBalance





after executing this i got this  TEST SOLUTION ERROR which i don't know what it means





{"finished": true, "success": [{"fullName": "test_balance", "passedSpecNumber": 1}, {"fullName": "test_deposit", "passedSpecNumber": 2}, {"fullName": "test_sub_class", "passedSpecNumber": 3}, {"fullName": "test_withdraw", "passedSpecNumber": 4}], "passed": false, "started": true, "failures": [{"failedSpecNumber": 1, "fullName": "test_invalid_operation", "failedExpectations": [{"message": "Failure in line 23, in test_invalid_operation\n    self.assertEqual(self.my_account.withdraw(1000), \"invalid transaction\", msg='Invalid transaction')\nAssertionError: Invalid transaction\n"}]}], "specs": {"count": 5, "pendingCount": 0, "time": "0.000065"}}
-910
invalid transaction



SO please what is wrong with my code, does it not meet the requirement of the "test case" given above in the question? 
Thanks in advance