This one is workable for me.
# Step 1: Update your repositories
$ sudo apt-get update
# Step 2: Install pip for Python 3
$ sudo apt-get python3-dev
$ sudo apt install python3-pip
# Step 3: Use pip to install virtualenv (no sudo)
$ pip3 install virtualenv
# Step 4: Create your Python 3 virtual environment
$ python3 -m virtualenv -p python3 env3
# Step 5: Activate the new Python 3 environment.
$ source env3/bin/activate
# you can make sure you are now working with Python 3
$ python --version
