I have a small function which returns nothing but creates csv file instead.
I would like to unittest it if given output csv file contains proper data.
How can I achieve that?

function

```
def create_csv(input, output)
    df = pd.read_csv(input, names=['number1', 'number2'])
    df.number1 *= 2
    df.number2 *= 5
    df.to_csv(output, index=False, header=False)

```