I have just started to study Python and I am now in the process of doing some exercises.

Specifically, this exercise asks to write a Python program to sum three given integers. However, if two values are equal sum will be zero.

This is my code:

```
   from sys import argv
   script, x, y, z = argv

   def sum(x, y, z):  
       if x == y or y == z or x==z:  
          sum = 0  
       else:  
          sum = x + y + z  
       return sum  
   print (sum)

```

I am opening the script in WindowPowerShell specifying the script name (es3.py) and the three variables, e.g: 1 2 3.

However I get the following message:

```
<function sum at 0x0000000001E0F048>

```

instead of the result I was expecting. 

Does anyone have any ideas of why this is happening?

Thanks.