Unable to locate libssh2 package

I was following this tutorial https://www.digitalocean.com/community/tutorials/how-to-configure-secure-updates-and-installations-in-wordpress-on-ubuntu

and I tried installing libssh2-1 package using the following command

 sudo apt install libssh2–1-dev libssh2–1

and I got an error message

E: Unable to locate package libssh2–1-dev
E: Unable to locate package libssh2–1

Now it is my understanding that these packages are part of default Ubuntu installation so why are these packages missing? What should I do? I already tried apt update command but it doesn’t help.