fhub-track allows you to fork a project with only the code you need, change for your necessity, and keep track of the changes from the base repository.
The project gotools has an internal tool for diff that is an internal go package. Using the fhub-track, forked only the diff tool code, when has new release the fhub-track keeps the code updated. The new project with the public diff tool galgotech/gotools.
fhub-track is distributed under AGPL-3.0-only.