code: def ping(token_or_hostname=None):
      
      if not token_or_hostname:
          return "Pong!"
      node = nago.core.get_node(token_or_hostname)
      if not node and token_or_hostname in ('master', 'server'):
          token_or_hostname = nago.settings.get_option('server')
          node = nago.core.get_node(token_or_hostname)
      if not node:
          try:
              address = socket.gethostbyname(token_or_hostname)
              node = nago.core.Node()
              node['host_name'] = token_or_hostname
              node['address'] = address
              node['access'] = 'node'
              if token_or_hostname == nago.settings.get_option('server'):
                  node['access'] = 'master'
              node.save()
          except Exception:
              raise Exception("'%s' was not found in list of known hosts, and does not resolve to a valid address" % token_or_hostname)
      return node.send_command('nodes', 'ping')
docs: Send an echo request to a nago host.
  
      Arguments:
          token_or_host_name  -- The remote node to ping
                              If node is not provided, simply return pong
                              You can use the special nodenames "server" or "master"