Is it possible to make numbered beta versions like in npm?

[goto40]

With NPM you can make numbered beta versions, like 1.2.3-beta.0.
After this you can "prerelease" any number of betas until you finalize your version... (1.2.3-beta.1, 1.2.3-beta.2, ..., 1.2.3-beta.18, 1.2.3)

Is this already possible with bumpversion?
(by the way: cool tool you created!)