I have these two lines of code in a program

```
res = Counter(test_str)
res = max(res, key=res.get)

```

however, I cannot seem to understand the `key=res.get`. I know that it sorts the keys of the dictionary (res) by the values but I thought the get() method required a mandatory "key" parameter? How can it be just `.get` and not `.get(key=)`?