Strings have a split method that works like this: 

>>> a = "this is a sentence"
>>> a.split()
['this', 'is', 'a', 'sentence']
>>> 

Knwoing this write a program that acts as a vending machine as illustrated below: 

a) you can enter names of coins, one per line or any number per line
b) the program updates the balance as it recognizes the coins
c) you can stop the program with bye (alone on a line)

>>> 
Enter coins: bye
Thanks for using this program.
>>> ================================ RESTART ================================
>>> 
Enter coins: dime
balance is now: $0.10
Enter coins: dollar dime dime
balance is now: $1.10
balance is now: $1.20
balance is now: $1.30
Enter coins: quarter cent
balance is now: $1.30
balance is now: $1.31
Enter coins: cent cent cent
balance is now: $1.32
balance is now: $1.33
balance is now: $1.34
Enter coins: dime nickel dime dime nickel
balance is now: $1.44
balance is now: $1.49
balance is now: $1.59
balance is now: $1.69
balance is now: $1.74
Enter coins: bye
Thanks for using this program.
>>> 

The program should report bad coins:

Enter coins: dime dime mark dinar nickel ruble
balance is now: $0.10
balance is now: $0.20
I don't understand mark
balance is now: $0.20
I don't understand dinar
balance is now: $0.20
balance is now: $0.25
I don't understand ruble
balance is now: $0.25
Enter coins: quarter
balance is now: $0.25
Enter coins: shekel
I don't understand shekel
balance is now: $0.25
Enter coins: bye
Thanks for using this program.
>>> 

The program should ignore empty lines: 

>>> 
Enter coins: 
Enter coins: 
Enter coins: 
Enter coins: dime
balance is now: $0.10
Enter coins: 
Enter coins: 
Enter coins: 
Enter coins: dime
balance is now: $0.20
Enter coins: nothing
I don't understand nothing
balance is now: $0.20
Enter coins: bye
Thanks for using this program.
>>>