Create a new val, then use the proper exports depending on what version you want to install:

Create val
// install stable version
export { stable } from "https://esm.town/v/pomdtr/example_release"

Create val
// install dev version
export { dev } from "https://esm.town/v/pomdtr/example_release"

Create val
// install canary version
export { canary } from "https://esm.town/v/pomdtr/example_release"