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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 _crop_box(self, size):
 """ Helper that calculates the crop box for the offset within the image. :param size: The width and height of the image composition. :type size: tuple :returns: The bounding box of the image, given ``size``. :rtype: tuple """

        (left, top) = self.offset
        right = left + min(size[0], self.width)
        bottom = top + min(size[1], self.height)

        return (left, top, right, bottom)