class_docstr: DummyPreemptContext is a PreemptContext where should_preempt() always returns False.
class_docstr_tok: ["DummyPreemptContext","is","a","PreemptContext","where","should_preempt","(",")","always","returns","False","."]
code: def start(self) -> "PreemptContext":
      if self._started:
          raise RuntimeError(
              "you cannot call PreemptContext.start() multiple times"
          )
      self._started = True
      return self
  
imports: import enum
  import logging
  import threading
  import time
  from typing import Any, Optional
  import requests
  from determined import core
  from determined.common import api
label_desc: Use image node_id 2 for calling the DummyPreemptContext obj's underlying member method code with example usage: obj.start() and returns: self