Save the `Spectrum1D` object to the specified filename.
        
        :param filename:
            The filename to save the Spectrum1D object to.

        :type filename:
            str

        :param clobber: [optional]
            Whether to overwrite the `filename` if it already exists.

        :type clobber:
            bool

        :raises IOError:
            If the filename exists and we were not asked to clobber it.

def save(self, filename, clobber=True, **kwargs):
        """
        Save the `Spectrum1D` object to the specified filename.
        
        :param filename:
            The filename to save the Spectrum1D object to.

        :type filename:
            str

        :param clobber: [optional]
            Whether to overwrite the `filename` if it already exists.

        :type clobber:
            bool

        :raises IOError:
            If the filename exists and we were not asked to clobber it.
        """
        
        if os.path.exists(filename) and not clobber:
            raise IOError("filename '{0}' exists and we have been asked not to"\
                " clobber it".format(filename))
        
        if not filename.endswith('fits'):
            # ASCII
            data = np.hstack([
                self.disp.reshape(-1, 1),
                self.flux.reshape(-1, 1),
                self.variance.reshape(-1, 1)
                ])
            return np.savetxt(filename, data, **kwargs)
            
        else:          
            # Create a tabular FITS format
            disp = fits.Column(name='disp', format='1D', array=self.disp)
            flux = fits.Column(name='flux', format='1D', array=self.flux)
            var = fits.Column(name='variance', format='1D', array=self.variance)
            table_hdu = fits.new_table([disp, flux, var])

            # Create Primary HDU
            hdu = fits.PrimaryHDU()

            # Update primary HDU with headers
            for key, value in self.headers.iteritems():
                if len(key) > 8: # To deal with ESO compatibility
                    hdu.header.update('HIERARCH {}'.format(key), value)

                try:
                    hdu.header.update(key, value)
                except ValueError:
                    logger.warn("Could not save header key/value combination: "\
                        "{0} = {1}".format(key, value))

            # Create HDU list with our tables
            hdulist = fits.HDUList([hdu, table_hdu])
            return hdulist.writeto(filename, clobber=clobber, **kwargs)