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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_nadir_pixel(earth_mask, sector):
 """Find the nadir pixel Args: earth_mask: Mask identifying earth and space pixels sector: Specifies the scanned sector Returns: nadir row, nadir column """

        if sector == FULL_DISC:
            logger.debug('Computing nadir pixel')

            # The earth is not centered in the image, compute bounding box
            # of the earth disc first
            rmin, rmax, cmin, cmax = bbox(earth_mask)

            # The nadir pixel is approximately at the centre of the earth disk
            nadir_row = rmin + (rmax - rmin) // 2
            nadir_col = cmin + (cmax - cmin) // 2

            return nadir_row, nadir_col

        return None, None