When we initialize a HashMap, we can but don't have to repeat the type of its key-value pairs.

<> is called the diamond. Using it, we don't have to re-specify our HashMap's types upon initialization. That's called type inference.

Psst: we're using Integer, an object that contains an int-type value, because HashMaps only take objects.

Yikes! The fact that we don't have to repeat the type goes for both the key and the value. Let's try a shorthand initialization instead.