Function pull_step 

pub fn pull_step(forward: &CoordinatedForward, real_index: &Path) -> PullStep

What: Decide what to do with a git pull, and run its fetch when the merge half can be completed here; real_index is the index the working tree update waits on. Why: Everything before the fetch decides from the command line, the settings and the repository’s state, so a pull this cannot mirror starts nothing; after the fetch, a FETCH_HEAD that does not list exactly one head goes back to native Git’s whole pull, which fetches again and words the refusal itself.

In TS you’d write (pseudocode):

async function pullStep(forward: CoordinatedForward, realIndex: string): Promise<PullStep>;