install python 3.9 linux

# Want to do this first usually
sudo apt update

sudo apt install software-properties-common
# A repo for python3.9 that works
sudo add-apt-repository ppa:deadsnakes/ppa
sudo apt install python3.9
# Checking that it worked
python3.9 --version
# Now to add venv - ensurepip
sudo apt-get install python3.9-venv

sudo python3.9 -m venv <my_env_name>

CXX="/usr/bin/g++"              \
./configure --prefix=/usr       \
            --enable-shared     \
            --with-system-expat \
            --with-system-ffi   \
            --with-ensurepip=yes &&
make