code: def install_virtualenv(parser_args):
      
      python_version = '.'.join(str(v) for v in sys.version_info[:2])
      sys.stdout.write('Installing Python {0} virtualenv into {1} \n'.format(python_version, VE_ROOT))
      if sys.version_info < (3, 3):
          install_virtualenv_p2(VE_ROOT, python_version)
      else:
          install_virtualenv_p3(VE_ROOT, python_version)
docs: Installs virtual environment