def getExtensions(self, extname='SCI', section=None):
        """ Return the list of EXTVER values for extensions with name specified
        in extname.

        """
        if section is None:
            numext = 0
            section = []
            for hdu in self._image:
                if 'extname' in hdu.header and hdu.header['extname'] == extname:
                    section.append(hdu.header['extver'])
        else:
            if not isinstance(section,list):
                section = [section]

        return section