docs: def _setup_virtualenv():
      """ Setup and install virtualenv """
      print("Downloading virtualenv...")
      import gzip, tarfile, io, tempfile, shutil
      tf = tarfile.open(fileobj=io.BytesIO(urlopen(VIRTUALENV_URL).read()))
      temp_folder = tempfile.mkdtemp()
      tf.extractall(temp_folder)
      print("Calling virtualenv...")
      subprocess.call([sys.executable, os.path.join(temp_folder, 'virtualenv-1.10', 'virtualenv.py'), 
                       '--no-setuptools', '--no-pip', '--no-site-packages', os.path.join(os.curdir, 'venv')])
      shutil.rmtree(temp_folder)