def apply_smoothing(self, smooth_fwhm):
if smooth_fwhm <= <NUM_LIT:0>:<EOL><INDENT>return<EOL><DEDENT>old_smooth_fwhm   = self._smooth_fwhm<EOL>self._smooth_fwhm = smooth_fwhm<EOL>try:<EOL><INDENT>data = self.get_data(smoothed=True, masked=True, safe_copy=True)<EOL><DEDENT>except ValueError as ve:<EOL><INDENT>self._smooth_fwhm = old_smooth_fwhm<EOL>raise<EOL><DEDENT>else:<EOL><INDENT>self._smooth_fwhm = smooth_fwhm<EOL>return data<EOL><DEDENT>
Set self._smooth_fwhm and then smooths the data.
        See boyle.nifti.smooth.smooth_imgs.

        Returns
        -------
        the smoothed data deepcopied.