docs: def inventory(self, all=False, ssid=None):
          """
          Returns a node inventory. If an API key is specified, only the nodes
           provisioned by this key will be returned.
  
          :return: { inventory }
          """
          if all or self.api_key is None:
              if ssid is not None:
                  return self._ssid_inventory(self.full_inventory, ssid)
              else:
                  return self.full_inventory
          else:
              if ssid is not None:
                  return self._ssid_inventory(self.self_inventory, ssid)
              else:
                  return self.self_inventory