Why does the sorted function's key parameter take key = lambda x: abs(x) but not abs()?

Question

Python

Hello!
Why does the sorted function's key parameter take key = lambda x: abs(x) but not abs()?
And for example, if I create a function like this:

def my_abs(x=0):
                  abs(x)

I still can't do this:
sorted(my_list, key = my_abs())

Answer 1

Because you are passing as key the result of calling the abs function, not the function itself. Remove parentheses.

Answer 2

Python 3.4 - everything works