JES account balance function help urgent!

[kidoman3 at gmail.com]

I am supposed to complete the following five functions, i have no idea how to do this. I will greatly appreciate any help

The following five functions allow you to maintain the running balance of an account and print out lines relating to each transaction.

You'll also need a global variable (balance?) to maintain the running balance of the account.

1. def setBalance(amt): # Defines (but doesn't print) the value of the account balance

2. def printBalance(): # Displays current balance as a money value with a heading

3. def printLedgerLine(date, amount, details): # with items (and the balance) spaced and formatted

4. def deposit (date, details, amount): # Alter the balance and print ledger line 

5. def withdraw(date, details, amount): # Alter the balance and print ledger line 

Your task is to:
complete the five (very short) functions by creating the code for the body of each function, and
demonstrate that you code works by calling the functions, as is demonstrated below.

So when these functions are called
e.g.

setBalance(500)
printBalance()
withdraw("17-12-2012", "BP - petrol", 72.50)
withdraw("19-12-2012", "Countdown", 55.50)
withdraw("20-12-2012", "munchies", 1.99)
withdraw("22-12-2012", "Vodafone", 20)
deposit ("23-12-2012", "Income", 225)
withdraw("24-12-2012", "Presents", 99.02)
printBalance()
The output is something like this:

Current Balance is $ 500.00
17-12-2012 BP - petrol $ 72.50 $ 427.50
19-12-2012 Countdown $ 55.50 $ 372.00
20-12-2012 munchies $ 1.99 $ 370.01
22-12-2012 Vodafone $ 20.00 $ 350.01
23-12-2012 Income $ 225.00 $ 575.01
24-12-2012 Presents $ 99.02 $ 475.99
Current Balance is $ 475.99

So far i got:
def setBalance(amount):
global balance
assert isinstance(amount,numbers.number)
balance = euros
printNow(balance)

Im not sure whats wrong, i only started programming a week ago, im so lost, please help me with this assignment
thnx