Switch between main (or master) and the most recent branch

main.fish

# Switches between a "main" branch ($BRANCHES) and the last checked-out branch.

function main
    set -l BRANCHES main master

    for branch in $BRANCHES;
        # Check if branch exists
        if [ (git branch --list $branch) ]
            # Check if branch is the currently checked-out branch
            if not [ (git branch --show-current) = $branch ]
                git checkout $branch
            else
                # Switch to the last used branch
                git checkout -
            end
            break
        end
    end
end