[Coursera] Python for everybody 5.2 Assignment

5.2 Write a program that repeatedly prompts a user for integer numbers until the user enters 'done'. Once 'done' is entered, print out the largest and smallest of the numbers. If the user enters anything other than a valid number catch it with a try,except and put out an appropriate message and ignore the number. Enter 7, 2, bob, 10, and 4 and match the output below.

largest = None
smallest = None

while True:
    inp = raw_input("Enter a number: ")
    if inp == "done" : break
    try:
        num = float(inp)
    except:
        print ("Invalid input")
        continue
    if smallest is None:
        smallest = num 
    if num > largest :
        largest = num
    elif num < smallest :
        smallest = num

def done(largest,smallest):
    print ("Maximum is", int(largest))  
    print ("Minimum is", int(smallest))

done(largest,smallest)

not work this code