code: def get_dynamips_id(self, project_id):
          
          self._dynamips_ids.setdefault(project_id, set())
          for dynamips_id in range(1, 4097):
              if dynamips_id not in self._dynamips_ids[project_id]:
                  self._dynamips_ids[project_id].add(dynamips_id)
                  return dynamips_id
          raise DynamipsError("Maximum number of Dynamips instances reached")
docs: :param project_id: UUID of the project
          :returns: a free dynamips id