code: func newDPKG() (packageManager, bool) {
  	_, err := exec.LookPath("dpkg-query")
  	if err != nil {
  		return nil, false
  	}
  	return dpkg{}, true
  }
docs: // newDPKG returns a Debian package manager. It returns (nil, false) if no such
  // package manager exists on the running machine.