code: def get_subscriptions(self, nodes=[]):
          
          if len(nodes) > 0:
              data = [node for node in self.get_clients() if node['name'] in nodes]
          else:
              data = self.get_clients()
          channels = []
          for client in data:
              if 'subscriptions' in client:
                  if isinstance(client['subscriptions'], list):
                      for channel in client['subscriptions']:
                          if channel not in channels:
                              channels.append(channel)
                  else:
                      if client['subscriptions'] not in channels:
                          channels.append(client['subscriptions'])
          return channels
docs: Returns all the channels where (optionally specified) nodes are subscribed