```py
rows = []
FILE = open("testing.txt", "r")
for blob in FILE: rows.append([int(i) for i in blob.split(" ")])

```

Here testing.txt contains

```
01 23 04   05 67
08 09 10
11
12

```

But when I run the code, I get the following error:

```
ValueError                                Traceback (most recent call last)
<ipython-input-1-2086c8bf9ab4> in <module>()
      1 rows = []
      2 FILE = open("testing.txt", "r")
----> 3 for blob in FILE: rows.append([int(i) for i in blob.split(" ")])

ValueError: invalid literal for int() with base 10: ''

```

So my question is: what's wrong with int()? I thought it's perfectly ok if the argument is an integer (so `int(5) == 5` for example). Thank you.