Draw a circle of 'radius' centered at (x, y)

def circle(self, clear_screen=True, x=50, y=50, radius=40, fill_color='black', outline_color='black'):
        """
        Draw a circle of 'radius' centered at (x, y)
        """

        if clear_screen:
            self.clear()

        x1 = x - radius
        y1 = y - radius
        x2 = x + radius
        y2 = y + radius

        return self.draw.ellipse((x1, y1, x2, y2), fill=fill_color, outline=outline_color)