? about "split" and strings

import string

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




def startup():

    fileerror = 0
    acct = Account(0) #create an instance of ACCOUNT to 0

    f = open("history.log","r")  #load history file
 
# history file format = "16July2003104356|D|45.00|45.00"
     while 1:
          lines = f.readlines(100000)
          if not lines: #stops at the end of the file
	break
          for line in lines:
	s = string.split (line,"|")
	if s[1] == "D":
	     acct.deposit(string.atoi(s[2]))
	elif s[1] == "W":
	      acct.withdraw(string.atoi(s[2]))
	print acct.getbalance() ," - - ", s[3] # error checking


# Begin Main
startup()

#split a string.
string_instance.split(char to split on)

#make the string upper case.
string_instance.upper()

#make the string lower case.
string_instance.lower()

#make the string title case.
string_instance.title()

#join a string.
string_to_join_with.join(list)

import string

from string import *