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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 radiance2tb(self, rad):
 """ Get the Tb from the radiance using the Planck function and the central wavelength of the band rad: Radiance in SI units """

        return radiance2tb(rad, self.rsr[self.bandname][self.detector]['central_wavelength'] * 1e-6)