**Notes**

The `functools`

library contains many items that allow you
to make the most out of lambda functions. A common example
is the `reduce`

function. We'll show a demonstration below.

```
from functools import reduce
numbers = [1, 2, 3, 4, 5]
# sum via reduce
reduce(lambda x, y: x + y, numbers)
# prod via reduce
reduce(lambda x, y: x * y, numbers)
```

Note that `reduce`

tells us **what** we are doing while the
`lambda`

function tells us **how** we are doing it.