hi guys： could anyone help me solve this problem? I am trying to install ROS indigo in Mac pro, and I follow this tutorial. however, after I run this command :

rosinstall_generator desktop_full --rosdistro indigo --deps --wet-only --tar > indigo-desktop-full-wet.rosinstall

the error come out, following is the error

Traceback (most recent call last):
  File "/usr/local/bin/rosinstall_generator", line 141, in <module>
    rc = main()
  File "/usr/local/bin/rosinstall_generator", line 129, in main
    upstream_version_tag=args.upstream, upstream_source_version=args.upstream_development)
  File "/usr/local/lib/python2.7/site-packages/rosinstall_generator/generator.py", line 249, in generate_rosinstall
    wet_package_names, unreleased_repo_names = _get_packages_for_repos(distro_name, repo_names)
  File "/usr/local/lib/python2.7/site-packages/rosinstall_generator/generator.py", line 93, in _get_packages_for_repos
    wet_distro = get_wet_distro(distro_name)
  File "/usr/local/lib/python2.7/site-packages/rosinstall_generator/generator.py", line 215, in get_wet_distro
    _wet_distro = _get_wet_distro(distro_name)
  File "/usr/local/lib/python2.7/site-packages/rosinstall_generator/distro.py", line 46, in get_distro
    return get_cached_distribution(index, distro_name)
  File "/usr/local/lib/python2.7/site-packages/rosdistro/__init__.py", line 134, in get_cached_distribution
    cache = get_distribution_cache(index, dist_name)
  File "/usr/local/lib/python2.7/site-packages/rosdistro/__init__.py", line 161, in get_distribution_cache
    yaml_gz_str = load_url(url, skip_decode=True)
  File "/usr/local/lib/python2.7/site-packages/rosdistro/loader.py", line 63, in load_url
    contents = fh.read()
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 355, in read
    data = self._sock.recv(rbufsize)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py", line 597, in read
    s = self.fp.read(amt)
  File "/usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 384, in read
    data = self._sock.recv(left)
socket.timeout: timed out

thanks advance