docstr: Run when a new worker enters the cluster
docstr_tok: ["Run","when","a","new","worker","enters","the","cluster"]
code: def add_worker(self, scheduler=None, worker=None, **kwargs):
      """Run when a new worker enters the cluster"""
      self.socket.send("add_worker", {"worker": worker})
  
file_path: distributed/distributed/diagnostics/websocket.py
imports: from __future__ import annotations
  from dask.utils import key_split
  from distributed.diagnostics.plugin import SchedulerPlugin
  from distributed.diagnostics.task_stream import colors
label_desc: Use image node_id 3 for calling the WebsocketPlugin obj's underlying member method code with example usage: obj.add_worker(scheduler, worker) without return types