'Get/set/modify the Cache-Control header (`HTTP spec section 14.9
<http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9>`_)'

def _cache_control__get(self):

    env = self.environ
    value = env.get('HTTP_CACHE_CONTROL', '')
    (cache_header, cache_obj) = env.get('webob._cache_control', (None, None))
    if ((cache_obj is not None) and (cache_header == value)):
        return cache_obj
    cache_obj = CacheControl.parse(value, updates_to=self._update_cache_control, type='request')
    env['webob._cache_control'] = (value, cache_obj)
    return cache_obj
