code: func (d *driver) ProgramExternalConnectivity(nid, eid string, options map[string]interface{}) error {
  	data := &api.ProgramExternalConnectivityRequest{
  		NetworkID:  nid,
  		EndpointID: eid,
  		Options:    options,
  	}
  	err := d.call("ProgramExternalConnectivity", data, &api.ProgramExternalConnectivityResponse{})
  	if err != nil && plugins.IsNotFound(err) {
  		// It is not mandatory yet to support this method
  		return nil
  	}
  	return err
  }
docs: // ProgramExternalConnectivity is invoked to program the rules to allow external connectivity for the endpoint.