Exercise 3.4. A function object is a value you can assign to a variable or pass as an argument. For example, do_twice is a function that takes a function object as an argument and calls it twice:

def do_twice(f):

f()

f()

Heres an example that uses do_twice to call a function named print_spam twice.

def print_spam():

print 'spam'

do_twice(print_spam)

1. Type this example into a script and test it.

2. Modify do_twice so that it takes two arguments, a function object and a value, and calls the function twice, passing the value as an argument.

3. Write a more general version of print_spam, called print_twice, that takes a string as a parameter and prints it twice.

4. Use the modified version of do_twice to call print_twice twice, passing 'spam' as an argument.

5. Define a new function called do_four that takes a function object and a value and calls the function four times, passing the value as a parameter. There should be only two statements in the body of this function, not four.