code: function copyFileSync(sourcePath, destPath) {
    var data = fs.readFileSync(sourcePath);
    var stat = fs.statSync(sourcePath);
    fs.writeFileSync(destPath, data);
    fs.chmodSync(destPath, stat.mode);
  }
docs: implementing it b/c we don't want to depend on fs.copyFileSync which appears only in node@8.x