install libssl1.0 code example

Example: install libssl1.0

# in this part I thought it better to use the add-apt-key tool
sudo apt-get install add-apt-key
sudo su -

add-apt-key --keyserver keyserver.ubuntu.com < the key that appeared in the error > 
exit

sudo apt update && apt-cache policy libssl1.0-dev
sudo apt-get install libssl1.0-dev