When using PIP for an installation operation, you run into this problem:

was later found to be caused by a change in the function in the library that updated PIP to 10.0.0.
solution:
sudo gedit /usr/bin/pip
Will the original:
from pip import main
if __name__ == '__main__':
sys.exit(main())
To:
from pip import __main__
if __name__ == '__main__':
sys.exit(__main__._main())
With respect to OK