Error with matplotlib

[Samir]

On Monday, 18 February 2019 at 18:27:17 UTC, Andre Pany wrote:
> Therefore python needs to be installed and also 
> matplotlib.pyplot.

Hi Andre,

I do have both python3 and matplotlib installed:

  $ python3
  Python 3.6.7 (default, Jan 10 2019, 01:15:48)
  [GCC 4.2.1 Compatible FreeBSD Clang 6.0.0 
(tags/RELEASE_600/final 326565)] on freebsd11
  Type "help", "copyright", "credits" or "license" for more 
information.
  >>> matplotlib.__version__
  '3.0.2'
  >>> import matplotlib.pyplot
  >>>

Do I have an issue with the way my dub.json file is configured?  
This is the first time I am using dub.  I also just copied and 
pasted the code in app.d straight from the matplotlib-d package 
page (http://code.dlang.org/packages/matplotlib-d).

Thanks
Samir