'Set expiration on this request.  This sets the response to
expire in the given seconds, and any other attributes are used
for cache_control (e.g., private=True, etc).'

def _cache_expires(self, seconds=0, **kw):

    if (seconds is True):
        seconds = 0
    elif isinstance(seconds, timedelta):
        seconds = timedelta_to_seconds(seconds)
    cache_control = self.cache_control
    if (seconds is None):
        pass
    elif (not seconds):
        cache_control.no_store = True
        cache_control.no_cache = True
        cache_control.must_revalidate = True
        cache_control.max_age = 0
        cache_control.post_check = 0
        cache_control.pre_check = 0
        self.expires = datetime.utcnow()
        if ('last-modified' not in self.headers):
            self.last_modified = datetime.utcnow()
        self.pragma = 'no-cache'
    else:
        cache_control.properties.clear()
        cache_control.max_age = seconds
        self.expires = (datetime.utcnow() + timedelta(seconds=seconds))
        self.pragma = None
    for (name, value) in kw.items():
        setattr(cache_control, name, value)
