The line is:

```
key1 = dictionary_name.get('key1', ['']) [0] or 0

```

I understand the `get` method and the default value but I have no clue what's happening with the `or` after the `)`. The line seems to have the function to read the value of a key out of a directory and return `0` if the value is `' '`.  

But how does the line, especially the boolean `or`, work in details?