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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 get_area_def(self, dsid):
 """Get the area definition of the datasets in the file. Only applicable for MSG products! """

        if self.pps:
            # PPS:
            raise NotImplementedError

        if dsid.name.endswith('_pal'):
            raise NotImplementedError

        proj_str, area_extent = self._get_projection()

        nlines, ncols = self.nc[dsid.name].shape

        area = get_area_def('some_area_name',
                            "On-the-fly area",
                            'geosmsg',
                            proj_str,
                            ncols,
                            nlines,
                            area_extent)

        return area