[FEATURE] Fix style code by PEP 8 for market.py

http://legacy.python.org/dev/peps/pep-0008/#id12
http://legacy.python.org/dev/peps/pep-0008/#id14
I don't think these comments which describe self-descriptive code add any context to the code reader. In fact, they are confusing, increase code size, and decrease maintainability. Comments should be added to explain **why** a piece of code was written, not what it does.

Also, these comments describing the function functionality should be [docstrings](http://legacy.python.org/dev/peps/pep-0257/), not comments. Let's switch to them.