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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def onScreen(x, y=None):
 """Returns whether the given xy coordinates are on the screen or not. Args: Either the arguments are two separate values, first arg for x and second for y, or there is a single argument of a sequence with two values, the first x and the second y. Example: onScreen(x, y) or onScreen([x, y]) Returns: bool: True if the xy coordinates are on the screen at its current resolution, otherwise False. """

    x, y = _unpackXY(x, y)
    x = int(x)
    y = int(y)

    width, height = platformModule._size()
    return 0 <= x < width and 0 <= y < height