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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 _calibrate_vis(radiance, k):
 """Convert VIS radiance to reflectance Note: Angle of incident radiation and annual variation of the earth-sun distance is not taken into account. A value of 100% corresponds to the radiance of a perfectly reflecting diffuse surface illuminated at normal incidence when the sun is at its annual-average distance from the Earth. TODO: Take angle of incident radiation (cos sza) and annual variation of the earth-sun distance into account. Reference: [VIS] Args: radiance: Radiance [mW m-2 cm-1 sr-1] k: pi / H, where H is the solar spectral irradiance at annual-average sun-earth distance, averaged over the spectral response function of the detector). Units of k: [m2 um sr W-1] Returns: Reflectance [%] """

        logger.debug('Calibrating to reflectance')
        refl = 100 * k * radiance
        return refl.clip(min=0)