}
    recordChangeDescriptions = shouldRecordChangeDescriptions;
     Capture initial values as of the time profiling starts.
     It's important we snapshot both the durations and the id-to-root map,
     since either of these may change during the profiling session
     (e.g. when a fiber is re-rendered or when a fiber gets removed).
    displayNamesByRootID = new Map();
    initialTreeBaseDurationsMap = new Map(idToTreeBaseDurationMap);
    initialIDToRootMap = new Map(idToRootMap);
    idToContextsMap = new Map();
    hook.getFiberRoots(rendererID).forEach(root => {
      const rootID = getFiberID(getPrimaryFiber(root.current));
      ((displayNamesByRootID: any): DisplayNamesByRootID).set(
        rootID,
        getDisplayNameForRoot(root.current),
      );
      if (shouldRecordChangeDescriptions) {
         Rec
         Fib
         so 
        crawlToInitializeContextsMap(root.current);
      }
    });
    isProfiling = true;
    profilingStartTime = getCurrentTime();
    rootToCommitProfilingMetadataMap = new Map();
  }
  function stopProfiling() {
    isProfiling = false;
    recordChangeDescriptions = false;