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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 calc_efficiency(self):
 """ Solar cell efficiency The efficiency is calculated according to Shockley & Queisser's :cite:`10.1063/1.1736034` Eq. 2.8. This method returns a :class:`float`. """

        cell_power = self.calc_power_density()
        solar_power = self.calc_blackbody_radiant_power_density()
        efficiency = cell_power/solar_power

        return efficiency.decompose().value