code: def __enter__(self):
      if self.__start_msg:
          output = self.__start_msg
      else:
          output = f"STARTING {self.__label}... "
      self.__handle.write(output)
      self.__handle.flush()
      self.__start_time = time.perf_counter_ns()
  
imports: import sys
  import time
label_desc: Use image node_id 2 for calling the TimerContext obj's underlying member method code with example usage: obj.__enter__() without return types