Delete local git branches with deleted remotes

zsh.rc

function orphaned-branches {
    git branch -vv | cut -c 3- | awk '$4 ~/gone\]/ { print $1 }'
}

function gitclean {
    git remote -v prune origin
    echo "WARNING: The following branches will be deleted!"
    RESPONSE=$(orphaned-branches)
    echo "$RESPONSE"
    echo
    echo "Are you sure (yN)?"
    read yn
    if [[ $yn =~ ^[yY]$ ]]
    then
        echo "$RESPONSE" | xargs git branch -D
    fi
}