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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 _vis_calibrate(self, data, key):
 """VIS channel calibration."""

        # radiance to reflectance taken as in mipp/xrit/MSG.py
        # again FCI User Guide is not clear on how to do this

        sirr = self.nc[
            '/data/{}/measured/channel_effective_solar_irradiance'
            .format(key.name)][...]

        # reflectance = radiance / sirr * 100
        data.data[:] /= sirr
        data.data[:] *= 100