code: def transition(self, key, start, finish, *args, **kwargs):
      if start == "processing":
          if key not in self.scheduler.tasks:
              return
          if not kwargs.get("startstops"):
              # Other methods require `kwargs` to have a non-empty list of `startstops`
              return
          kwargs["key"] = key
          if finish == "memory" or finish == "erred":
              self.buffer.append(kwargs)
              self.index += 1
  
file_path: distributed/distributed/diagnostics/task_stream.py
imports: from __future__ import annotations
  import logging
  from collections import deque
  import dask
  from dask.utils import format_time, key_split, parse_timedelta
  from distributed.diagnostics.plugin import SchedulerPlugin
  from distributed.diagnostics.progress_stream import color_of
  from distributed.metrics import time
label_desc: Use image node_id 2 for calling the TaskStreamPlugin obj's underlying member method code with example usage: obj.transition(key, start, finish) without return types