Refactor some code to be readable

[hschilling]

Some code is using short-circuit boolean expressions that make it difficult to interpret the code.

As an example

mag_paper = (mag_index >= 0 and mag_res[mag_index]) or {}

would be better written as

mag_paper = {}
if mag_index >= 0:
    mag_paper = mag_res.get(mag_index, {})