Improvement - Update gateway code from python 2 to python 3

Python 2 is no longer supported, we should migrate to python 3.

Python 2 was officially sunset on Jan 1, 2020: https://www.python.org/doc/sunset-python-2/

Prior to doing this, it would be helpful to reformat some of the code - there’s a mix of tabs and spaces (switch to only using spaces)

There’s a python tool called 2to3 that should help with this conversion.

# TODO - add some of the 2to3 examples here

One task to complete prior to starting is:

• Cleanup some of the indentation in the code - there mixed tabs and spaces all over the place, this should be converted to use spaces. This is used by the official python style guide: https://www.youtube.com/