Problems with running examples / installation

[jvolker]

Thanks a lot for creating this software!

I had a few initial problems setting this up on my machine:

macOS 10.13.3
Python 2.7.10

I was getting these errors:

• NameError: global name 'numpy' is not defined
• ImportError: No module named cairo

What I had to do to make some of the examples work:

• pip install numpy
• pip install cairocffi and change import cairo in drawing.py to import cairocffi as cairo