If both python 2 and python 3 are installed on your machine, use the following:

pip3 install --user -r "requirements.txt"

If you have only python3 installed on your machine, use the following:

pip install --user -r "requirements.txt"

Some samples are dependent on Tkintker and PIL. You can install them on debian systems with the following commands:

sudo apt install python3-pil.imagetk