How to generate the privateStorefrontToken as required for deploying a Hydrogen store to Vercel?

[shopdoo]

As per this page in the documentation, in order to deploy a Hydrogen app to a non-Oxygen hosting service, such as Vercel, we need to specify a privateStorefrontToken as an environment variable in hydrogen.config.js

https://shopify.dev/docs/custom-storefronts/hydrogen/deployment

How do you generate this access token? There is no apparent documentation on this.