Hello everyone!
Currently working on the “Making simple inter-canister calls” tutorial, I found that the git clone git@github.com:dfinity-lab/linkedup.git command didn’t works for me.
I got the following message:
Cloning into ‘linkedup’…
The authenticity of host ‘github.com (140.82.121.4)’ can’t be established.
RSA key fingerprint is SHA256:nThbg6kXUpJWGl7E1IGOCspRomTxdCARLviKw6E5SY8.
Are you sure you want to continue connecting (yes/no/[fingerprint])? y
Please type ‘yes’, ‘no’ or the fingerprint: yes
Warning: Permanently added ‘github.com,140.82.121.4’ (RSA) to the list of known hosts.
git@github.com: Permission denied (publickey).
fatal: Could not read from remote repository.
However, I found a workaround by copy pasting the link from the GitHub repository: git clone https://github.com/dfinity-lab/linkedup.git.
This is just for your information! 
Honestly, once I found the solution I didn’t go further.
Have a nice day (or night)!