I am on Mac `11.6 (20G165)`.

I have node.js v10 installed and want to upgrade to v12.

However, when I type `brew upgrade node`, I got this:

```
$brew upgrade node
Error: node not installed

```

I think it's because I didn't install node via `homebrew` before. But it's been such a long time and I couldn't remember what exact source/channel did I choose to install node long ago.

So what I can do to fix all this?