Cloud9にPython3.6をインストール

sudo add-apt-repository ppa:jonathonf/python-3.6
sudo apt-get update
sudo apt-get install python3.6

wget https://bootstrap.pypa.io/ez_setup.py
sudo -H python3.6 ez_setup.py

wget https://bootstrap.pypa.io/get-pip.py
sudo -H python3.6 get-pip.py

sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.4 1
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 2
sudo update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.6 3
sudo update-alternatives --config python3

sudo -H pip3 install pipenv
sudo -H pip3 install setuptools

pipenv --three

Python Versionは「Python 3」を選択

PYTHONPATHに「:/usr/local/lib/python3.6/dist-packages」を追加

import sys

print("sys.version=", sys.version)
# バージョン確認
python3 -V
pip3 -V