code: function getFiles(base, dir = '', results = []) {
              const files = fs.readdirSync(path.join(base, dir));
              for (const file of files) {
                  const relativeToBase = path.join(dir, file);
                  if (fs.statSync(path.join(base, relativeToBase)).isDirectory()) {
                      getFiles(base, relativeToBase, results);
                  } else {
                      results.push(relativeToBase);
                  }
              }
              return results;
          }
docs: Rewrite GitHub urls 
  Avoiding sync methods here is... difficult.
  @param {string} base
  @param {string} dir
  @param {string[]} results
  @returns {string[]}