Function tag 

pub fn tag<W: Write>(
    wok_config: &mut Config,
    umbrella: &Repo,
    stdout: &mut W,
    tag_name: Option<&str>,
    sign: bool,
    message: Option<&str>,
    push: bool,
    all: bool,
    include_umbrella: bool,
    target_repos: &[PathBuf],
) -> Result<()>

Legacy function for backward compatibility with tests