code: def take_dynamips_id(self, project_id, dynamips_id):
          
          self._dynamips_ids.setdefault(project_id, set())
          if dynamips_id in self._dynamips_ids[project_id]:
              raise DynamipsError("Dynamips identifier {} is already used by another router".format(dynamips_id))
          self._dynamips_ids[project_id].add(dynamips_id)
docs: Reserve a dynamips id or raise an error
  
          :param project_id: UUID of the project
          :param dynamips_id: Asked id