pub fn download<W>(&self, writer: &mut W, family: &str) -> Result<(), FontError>
        where W: Write
    {
        let client = Client::new();

        // make sure local path exists
        let path = dirs::font_cache().ok_or(FontError::FontDirectory)?;
        dirs::make_rec_dir(&path)?;

        // download and install each variant of the given font family
        let font = self.get_family(family).ok_or(FontError::FontNotFound)?;
        for (variant, uri) in &font.files {
            let path = dirs::get_font_path(&path, family, &variant, &uri);

            // let the user know which font we are processing
            let message = format!("Installing '{:?}'\n", path);
            eprint!("fontfinder: {}", message);
            let _ = writer.write(message.as_bytes());

            // download and store locally
            let mut file = OpenOptions::new().create(true).write(true).open(&path)?;
            let mut data = client.get(uri.as_str()).send()?;
            io::copy(&mut data, &mut file)?;
        }

        Ok(())
}