pipenv` command isn't availble in the image, devcafe/cmake-cookbook_ubuntu-18.04

Hi

I'm trying to replicate the steps given in your accompanying book at page 10 after having installed the Docer image.

The third step `pipenv install --three` cannot be executed, due to the `pipenv` command isn't availble in the image, devcafe/cmake-cookbook_ubuntu-18.04.

What am I doing wrong?...

Thank you.