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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 extrema(self, x0, y0, w, h):
 """ Returns the minimum and maximum values contained in a given area. :param x0: Starting x index. :param y0: Starting y index. :param w: Width of the area to scan. :param h: Height of the area to scan. :return: Tuple containing the minimum and maximum values of the given area. """

        minimum = 9223372036854775807
        maximum = 0
        for y in range(y0, y0 + h):
            for x in range(x0, x0 + w):
                value = self[x, y]
                if value != self.filler:
                    minimum = min(minimum, value)
                    maximum = max(maximum, value)
        return minimum, maximum