Docker installation

Docker installation.txt

sudo apt install apt-transport-https ca-certificates curl software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu artful stable"
sudo apt update
sudo apt install docker-ce


when i install from https://docs.docker.com/install/linux/docker-ce/ubuntu/#install-docker-ce-1
i get 

E: Package 'docker-ce' has no installation candidate

so i search and get the above commends
source 
https://unix.stackexchange.com/questions/363048/unable-to-locate-package-docker-ce-on-a-64bit-ubuntu