Unable to locate package python3.8-ven code example

Example 1: E: Unable to locate package python3-pip

sudo add-apt-repository universe
sudo apt-get update

Example 2: unable to locate package python3.6-venv

apt-get update \
&& apt-get install -y software-properties-common curl \
&& add-apt-repository ppa:deadsnakes/ppa \
&& apt-get update \
&& apt-get install -y python3.6 python3.6-venv