解决安装ipython报错prompt-toolkit 1.0.15 has requirement six>=1.9.0, but you'll have six 1.4.1 which is in

• 解决报错
  prompt-toolkit 1.0.15 has requirement six>=1.9.0, but you’ll have six 1.4.1 which is incompatible.

pip install six --user -U
pip install ipython --user -U