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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 _init_refl3x(self, projectables):
 """Initiate the 3.x reflectance derivations."""

        if not Calculator:
            LOG.info("Couldn't load pyspectral")
            raise ImportError("No module named pyspectral.near_infrared_reflectance")
        _nir, _tb11 = projectables
        self._refl3x = Calculator(_nir.attrs['platform_name'], _nir.attrs['sensor'], _nir.attrs['name'])