I've made a code to repete a function process:

```
def do_twice(func, *args):
    func(func(args))
def div(number):
    print(number[0]/2)
do_twice(div, 8)

```

The expected output is:

```
4.0
2.0

```

But the output is:

```
4.0
TypeError: 'NoneType' object is not subscriptable

```

At this point I thought: Seems like `number` is `None` in the second round.
And my guess prooved as correct:

```
…
def div(number):
    print(number)                          # i know, actually i shouldn't call it div NOW...

# output:
4
None

```

What was my fault? Thanks in advance.