code: def online_networks(self) -> List[Dict]:
      networks = self.all_networks
  
      def check_network(network: Dict) -> Optional[Dict[Any, Any]]:
          url = (
              "http://"
              + network["host_or_ip"]
              + ":"
              + str(network["port"])
              + "/"
          )
          try:
              res = requests.get(url, timeout=DEFAULT_TIMEOUT)  # nosec
              online = "This is a PyGrid Network node." in res.text
          except Exception:
              online = False
  
          # networks without frontend have a /ping route in 0.7.0
          if not online:
              try:
                  ping_url = url + "ping"
                  res = requests.get(
                      ping_url, timeout=DEFAULT_TIMEOUT
                  )  # nosec
                  online = res.status_code == 200
              except Exception:
                  online = False
  
          if online:
              version = network.get("version", None)
              # Check if syft version was described in NetworkRegistry
              # If it's unknown, try to update it to an available version.
              if not version or version == "unknown":
                  # If not defined, try to ask in /syft/version endpoint (supported by 0.7.0)
                  try:
                      version_url = url + "api/v2/metadata"
                      res = requests.get(
                          version_url, timeout=DEFAULT_TIMEOUT
                      )  # nosec
                      if res.status_code == 200:
                          network["version"] = res.json()[
                              "syft_version"
                          ]
                      else:
                          network["version"] = "unknown"
                  except Exception:
                      network["version"] = "unknown"
              return network
          return None
  
      # We can use a with statement to ensure threads are cleaned up promptly
      with futures.ThreadPoolExecutor(max_workers=20) as executor:
          # map
          _online_networks = list(
              executor.map(
                  lambda network: check_network(network), networks
              )
          )
  
      online_networks = []
      for each in _online_networks:
          if each is not None:
              online_networks.append(each)
      return online_networks
  
imports: from __future__ import annotations
  from concurrent import futures
  from typing import Any
  from typing import Dict
  from typing import List
  from typing import Optional
  from typing import TYPE_CHECKING
  from typing import Tuple
  from typing import Union
  import pandas
  import requests
  from ..service.metadata.node_metadata import NodeMetadataJSON
  from ..service.network.network_service import NodePeer
  from ..service.response import SyftException
  from ..types.grid_url import GridURL
  from ..util.constants import DEFAULT_TIMEOUT
  from ..util.logger import error
  from ..util.logger import warning
  from .enclave_client import EnclaveClient
label_desc: Use image node_id 2 for calling the NetworkRegistry obj's underlying member method code with example usage: obj.online_networks() and returns: online_networks, None, network