The code is for a complete chess game, including a gui with piece sprites and mouse input. A couple screenshots of the gui can be found in the photos folder.
There are three files of python code: chessboard, window, and main.

Chessboard contains classes for under-the-hood chess logic, defining legal moves and storing the state of the board.
Window draws the board onscreen, takes input from the user, and refreshes the gui whenever a piece is moved.
Main is responsible for executing the code defined in window.

Extra features:
Square of the selected piece turns red, so you don't accidentally make a move
If you attempt to make an illegal move it just doesn't work, and the square turns back to normal colors
Gui changes dimensions to fit the screen of the user