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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 _rgb2ycbcr(self, mode):
 """Convert the image from RGB mode to YCbCr."""


        self._check_modes(("RGB", "RGBA"))

        (self.channels[0], self.channels[1], self.channels[2]) = \
            rgb2ycbcr(self.channels[0],
                      self.channels[1],
                      self.channels[2])

        if self.fill_value is not None:
            self.fill_value[0:3] = rgb2ycbcr(self.fill_value[0],
                                             self.fill_value[1],
                                             self.fill_value[2])

        self.mode = mode