About class interface

First of all constructor. Order of params looking strange - y, x, dx, dy. Better to use more tradional order: x, y, dx, dy. If my worker will create classes with interface like in this task i will fire him. Another moment is corners function. Dictionary not needed there at all. Tuple is more then enought. Even if we use dictionary - its bad style to use "west-north" key instead "WE" for example. So, as i think this example teaching people how TO NOT create classes inteface.