Python is an easy to enter language, but having no guidelines has resulted in a rather messy codebase for gnome-music in my opinion. It would be nice to have music act both as an entry-level project and an example of clean Gtk/GNOME PyGI application development.

I propose to adopt a few guidelines for how to contribute to gnome-music and step-by-step move it to a cleaner state.

I suggest updating slowly as parts get rewritten naturally, not in one giant step. Updating probably per function as parts of a function get updated. 

Accepted guidelines should be eventually put in a document in the source tree.

Suggested guidelines: 

* Adhere to PEP-8 ( https://www.python.org/dev/peps/pep-0008/ )
 * function notation with underscores (new_function)
 * private variables and functions prefixed with _
 * docstrings for functions
 * etc.

* Following from PEP-8 is PEP-257 on Docstrings

* Use PyGI shorthands for accessing GtkTreeModel/GtkTreeStore
 * store[iter][column]
 * see https://python-gtk-3-tutorial.readthedocs.org/en/latest/treeview.html for details

* comment GtkTreeStore/GtkListStore with actual value number & description for clarity

store = Gtk.ListStore(
            str, #  1 - Name
            int, #  2 - Number
            )

* All tracker interaction in Query.py

* All Grilo interaction in Grilo.py

* All functions need to have @log decorator