I have the following dictionary:

```
sites = {
    'stackoverflow': 1,
    'superuser': 2,
    'meta': 3,
    'serverfault': 4,
    'mathoverflow': 5
}

```

To check if there are more than one key available in the above dictionary, I will do something like:

```
'stackoverflow' in sites and 'serverfault' in sites

```

The above is maintainable with only 2 key lookups. Is there a better way to handle checking a large number of keys in a very big dictionary?