tkinter virus

def _create_circle(self, x, y, r, **kwargs):
    """Create a circle

    x the abscissa of centre
    y the ordinate of centre
    r the radius of circle
    **kwargs optional arguments
    return the drawing of a circle
    """
    return self.create_oval(x-r, y-r, x+r, y+r, **kwargs)
tk.Canvas.create_circle = _create_circle

def _coords_circle(self, target, x, y, r, **kwargs):
    """Define a circle

    target the circle object
    x the abscissa of centre
    y the ordinate of centre
    r the radius of circle
    **kwargs optional arguments
    return the circle drawing with updated coordinates
    """
    return self.coords(target, x-r, y-r, x+r, y+r, **kwargs)
tk.Canvas.coords_circle = _coords_circle

def create(balls, canvas):
    """Create a drawing item for each solver.Ball object

    balls the list of solver.Ball objects
    canvas the Tkinter.Canvas oject
    return a dictionary with solver.Ball objects as keys and their circle drawings as items
    """
    return {ball: canvas.create_circle(ball.position[0], ball.position[1], ball.radius, fill="white") for ball in balls}

def update(drawing, canvas, step, size):
    """Update the drawing items for a time step

    drawing the dictionary of drawing items
    canvas the Tkinter.Canvas oject
    step the time step
    size the medium size
    """
    balls = drawing.keys()
    solver.solve_step(balls, step, size)
    for ball in balls:
        canvas.coords_circle(drawing[ball], ball.position[0], ball.position[1], ball.radius)
    canvas.update()