I'm trying to create a function that will find the sum of the elements of one column of a 2D list, but only the one specific column. I can find plenty of examples of how to find the sum for every column in the list, but not one that only gives me the one specific column. And the list has to be from a different function. 

```
def sumColumn(matrix, columnIndex):
(No idea what on earth to put here...)
return total

```