code: def add_site(self, name, site_elements=None):
          
          site_elements = site_elements if site_elements else []
          return self.sites.create(
              name, site_elements)
docs: Add a VPN site with site elements to this engine.
          VPN sites identify the sites with protected networks
          to be included in the VPN.
          Add a network and new VPN site::
          
              >>> net = Network.get_or_create(name='wireless', ipv4_network='192.168.5.0/24')
              >>> engine.vpn.add_site(name='wireless', site_elements=[net])
              VPNSite(name=wireless)
              >>> list(engine.vpn.sites)
              [VPNSite(name=dingo - Primary Site), VPNSite(name=wireless)]
          
          :param str name: name for VPN site
          :param list site_elements: network elements for VPN site
          :type site_elements: list(str,Element)
          :raises ElementNotFound: if site element is not found
          :raises UpdateElementFailed: failed to add vpn site
          :rtype: VPNSite
          
          .. note:: Update is immediate for this operation.