The browser JS displays: Widgets are not available. Please install widgetsnbextension or ipywidgets 4.0

# Method 1
pip install ipywidgets
jupyter nbextension enable --py widgetsnbextension
# Method 2
conda install -c conda-forge ipywidgets

fastpbkdf2 0.2 out of commission:

E: Package ‘libffi-dev’ has no installation candidate

ubuntu@VM-0-9-ubuntu:~$ sudo apt-get install libffi-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package libffi-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'libffi-dev' has no installation candidate

Use the following solution

sudo apt-get update
sudo apt-get install libnl-3-dev

The following error:
error: Command ‘x86_ 64 Linux GNU GCC ‘failed with exit status 1
solution:

sudo apt-get install build-essential python3-dev libssl-dev libffi-dev libxml2 libxml2-dev libxslt1-dev zlib1g-dev

Jupyter modify theme