Function install_appendix 

pub fn install_appendix(
    project_dir: &Path,
    install_path: &Path,
    dist_url: &str,
    transport_options: Option<&Value>,
) -> Result<String>

getInstallOperationAppendix: what follows the operation line — : Source already present when the install path already resolves to the source, else the strategy and the dist url as written.