'Sets the content and caching headers on the response.
.. versionadded:: 3.1'

def set_headers(self):

    self.set_header('Accept-Ranges', 'bytes')
    self.set_etag_header()
    if (self.modified is not None):
        self.set_header('Last-Modified', self.modified)
    content_type = self.get_content_type()
    if content_type:
        self.set_header('Content-Type', content_type)
    cache_time = self.get_cache_time(self.path, self.modified, content_type)
    if (cache_time > 0):
        self.set_header('Expires', (datetime.datetime.utcnow() + datetime.timedelta(seconds=cache_time)))
        self.set_header('Cache-Control', ('max-age=' + str(cache_time)))
    self.set_extra_headers(self.path)
