code: def __enter__(self):
      self.start_time = time.perf_counter()
      # the `Windows` case is tested, but not that
      # from which coverage is gathered which runs on ubuntu
      if platform.system() == "Windows":  # pragma: no cover
          return self
      self.pre_maxrss_bytes = resource.getrusage(
          resource.RUSAGE_SELF
      ).ru_maxrss
      return self
  
imports: import platform
  import time
label_desc: Use image node_id 2 for calling the PerformanceTracker obj's underlying member method code with example usage: obj.__enter__() and returns: self, self