Function git_repository::parallel::join

pub fn join<O1, O2>(
    left: impl FnOnce() -> O1 + Send, 
    right: impl FnOnce() -> O2 + Send
) -> (O1, O2) where
    O1: Send,
    O2: Send, 

Runs left and then right, one after another, returning their output when both are done.