>>> package = yarg.get('yarg')
            >>> v = "0.1.0"
            >>> r = package.release(v)
            >>> r.package_type
            u'wheel'

def package_type(self):
        """
            >>> package = yarg.get('yarg')
            >>> v = "0.1.0"
            >>> r = package.release(v)
            >>> r.package_type
            u'wheel'
        """
        mapping = {'bdist_egg': u'egg', 'bdist_wheel': u'wheel',
                   'sdist': u'source'}
        ptype = self._release['packagetype']
        if ptype in mapping.keys():
            return mapping[ptype]
        return ptype