ROS,ImportError: No module named em,i had try many methods in answer.ros.org,dont work ,plz help me

edit

for this link,i had tried the methods in it,but dont work for me;

https://answers.ros.org/question/2573...

i tried the following 6 command ,dont work

sudo pip2 uninstall em

The directory '/home/lzw/.cache/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Uninstalling em-0.4.0:


  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/DESCRIPTION.rst
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/INSTALLER
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/METADATA
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/RECORD 
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/WHEEL
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/entry_points.txt
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/metadata.json
  /usr/local/lib/python2.7/dist-packages/em-0.4.0.dist-info/top_level.txt
  /usr/local/lib/python2.7/dist-packages/em/__init__.py
  /usr/local/lib/python2.7/dist-packages/em/__init__.pyc
  /usr/local/lib/python2.7/dist-packages/em/locale/em.pot
  /usr/local/lib/python2.7/dist-packages/em/locale/fr/LC_MESSAGES/em.mo
  /usr/local/lib/python2.7/dist-packages/em/locale/ru/LC_MESSAGES/em.mo
  /usr/local/lib/python2.7/dist-packages/em/locale/uk/LC_MESSAGES/em.mo
  /usr/local/lib/python2.7/dist-packages/em/tests/__init__.py
  /usr/local/lib/python2.7/dist-packages/em/tests/__init__.pyc
  /usr/local/lib/python2.7/dist-packages/em/tests/basic.py
  /usr/local/lib/python2.7/dist-packages/em/tests/basic.pyc

Proceed (y/n)? y
  Successfully uninstalled em-0.4.0

sudo pip2 install empy

Requirement already satisfied: empy in /usr/lib/python2.7/dist-packages

sudo pip uninstall em

WARNING: Skipping em as it is not installed.

sudo pip install empty

Successfully installed Werkzeug-1.0.1 click-7.1.2 empty-0.4.4 flask-1.1.2 itsdangerous-1.1.0

sudo apt-get install python-empy

sudo apt-get install python3-empy