<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _mouseMoveDrag(moveOrDrag, x, y, xOffset, yOffset, duration, tween=linear, button=None):
 """Handles the actual move or drag event, since different platforms implement them differently. On Windows & Linux, a drag is a normal mouse move while a mouse button is held down. On OS X, a distinct "drag" event must be used instead. The code for moving and dragging the mouse is similar, so this function handles both. Users should call the moveTo() or dragTo() functions instead of calling _mouseMoveDrag(). Args: moveOrDrag (str):
 Either 'move' or 'drag', for the type of action this is. x (int, float, None, optional):
 How far left (for negative values) or right (for positive values) to move the cursor. 0 by default. y (int, float, None, optional):
 How far up (for negative values) or down (for positive values) to move the cursor. 0 by default. xOffset (int, float, None, optional):
 How far left (for negative values) or right (for positive values) to move the cursor. 0 by default. yOffset (int, float, None, optional):
 How far up (for negative values) or down (for positive values) to move the cursor. 0 by default. duration (float, optional):
 The amount of time it takes to move the mouse cursor to the new xy coordinates. If 0, then the mouse cursor is moved instantaneously. 0.0 by default. tween (func, optional):
 The tweening function used if the duration is not 0. A linear tween is used by default. See the tweens.py file for details. button (str, int, optional):
 The mouse button clicked. Must be one of 'left', 'middle', 'right' (or 1, 2, or 3) respectively. 'left' by default. Returns: None """


    # The move and drag code is similar, but OS X requires a special drag event instead of just a move event when dragging.
    # See https://stackoverflow.com/a/2696107/1893164
    assert moveOrDrag in ('move', 'drag'), "moveOrDrag must be in ('move', 'drag'), not %s" % (moveOrDrag)

    if sys.platform != 'darwin':
        moveOrDrag = 'move' # Only OS X needs the drag event specifically.

    xOffset = int(xOffset) if xOffset is not None else 0
    yOffset = int(yOffset) if yOffset is not None else 0

    if x is None and y is None and xOffset == 0 and yOffset == 0:
        return  # Special case for no mouse movement at all.

    startx, starty = position()

    x = int(x) if x is not None else startx
    y = int(y) if y is not None else starty

    # x, y, xOffset, yOffset are now int.
    x += xOffset
    y += yOffset

    width, height = size()

    # Make sure x and y are within the screen bounds.
    x = max(0, min(x, width - 1))
    y = max(0, min(y, height - 1))

    # If the duration is small enough, just move the cursor there instantly.
    steps = [(x, y)]

    if duration > MINIMUM_DURATION:
        # Non-instant moving/dragging involves tweening:
        num_steps = max(width, height)
        sleep_amount = duration / num_steps
        if sleep_amount < MINIMUM_SLEEP:
            num_steps = int(duration / MINIMUM_SLEEP)
            sleep_amount = duration / num_steps

        steps = [
            getPointOnLine(startx, starty, x, y, tween(n / num_steps))
            for n in range(num_steps)
        ]
        # Making sure the last position is the actual destination.
        steps.append((x, y))

    for tweenX, tweenY in steps:
        if len(steps) > 1:
            # A single step does not require tweening.
            time.sleep(sleep_amount)

        _failSafeCheck()
        tweenX = int(round(tweenX))
        tweenY = int(round(tweenY))
        if moveOrDrag == 'move':
            platformModule._moveTo(tweenX, tweenY)
        elif moveOrDrag == 'drag':
            platformModule._dragTo(tweenX, tweenY, button)
        else:
            raise NotImplementedError('Unknown value of moveOrDrag: {0}'.format(moveOrDrag))

    _failSafeCheck()