[Tutor] Class instance understanding = None

[David]

Hi Everyone,
I go through the archived [Tutor] mail list to find programs others have 
tried to do. I found one that would keep track of a petty cash fund. 
please point out my misunderstanding.
Here is what I started with;
<code>
#!/usr/bin/python

from reportlab.lib.normalDate import ND
#import cPickle as p
#import pprint

today = ND()

class Account:
     def __init__(self, initial):
         self.balance = initial
     def deposit(self, amt):
         self.balance = self.balance + amt
     def withdraw(self, amt):
         self.balance = self.balance - amt
     def getbalance(self):
         return self.balance
print 'The current date is: ', today.formatUS()


data = float('100.00')
a = Account(data)
p = a.getbalance()
print 'balance = ', p
remove_data = float('50.00')
w = a.withdraw(remove_data)
print "withdraw = ", w
add_data = float('50.00')
add = a.deposit(add_data)
print "deposit = ", add
</code>

results;
The current date is:  02/27/09
balance =  100.0
withdraw =  None
deposit =  None

expected results;
The current date is:  02/27/09
balance =  100.0
withdraw =  50.0
deposit =  100.0

thanks,
-david


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