Python go to def
<p>Hi there
First of all just let me say that I'm new in Python and this is for a school work so this should be done without advanced programing and global functions. Using Python 2.6.6 and WingIDE 101</p>

<p>I need a program to present the user with a menu. The user must pick an option and accordingly to is pick the program does what the user wants.</p>

<p>For example, in the code bellow (its not the actual code), if the user picks 1 it goes to the sum() function.</p>

<pre><code>def menu():
    print "What do you want? "
    print " 1 for sum"
    print " 2 for subtraction"
    pick = raw_input("please insert 1 or 2 ")
    if pick == "1":
       return sum()
    if pick == "2":
       return subtraction()
    else:
        menu()
menu()

def sum():
    return 8 + 4
def subtraction():
    return 8 - 4
</code></pre>

<p>I what to know how do I send, after my pick, the program to execute an determined definition.</p>

<p>Thanks</p>

<p>P.S. - running this gives me this error: 
Traceback (most recent call last):
  File "/usr/lib/wingide-101-3.2/src/debug/tserver/_sandbox.py", line 12, in 
  File "/usr/lib/wingide-101-3.2/src/debug/tserver/_sandbox.py", line 7, in menu
TypeError: sum expected at least 1 arguments, got 0</p>
