How I use prefixer in Lab 5.1?

I could not find "prefixer" in npm.

Should I define and create prefixer, my own function?

↓Must be wrong one in npm
"Prefix all rules in a CSS file
This library just packages up Substack's css-prefix library into an executable."

'use strict'

const sayHiTo = prefixer('Hello ')
const sayByeTo = prefixer('Goodbye ')
console.log(sayHiTo('Dave')) // prints 'Hello Dave'
console.log(sayHiTo('Annie')) // prints 'Hello Annie'
console.log(sayByeTo('Dave')) // prints 'Goodbye Dav'