lib/sync-file.js
function end() {
  this.writeBuffer(this.crc.value());
  fs.closeSync(this.fd);

  this.fd = null;
  this.crc = null;
  this.converter = null;
}
function end() {
  this.writeBuffer(this.crc.value());
  fs.closeSync(this.fd);

  this.fd = null;
  this.crc = null;
  this.converter = null;
}
Write the crc checksum to the file.