code: function instrument(component, callback, context) {
      var instrumentName, val, details, end;
      // Only instrument if there's at least one subscriber.
      if (_emberMetalInstrumentation.subscribers.length) {
        if (component) {
          instrumentName = component.instrumentName;
        } else {
          instrumentName = 'node';
        }
        details = {};
        if (component) {
          component.instrumentDetails(details);
        }
        end = _emberMetalInstrumentation._instrumentStart('render.' + instrumentName, function viewInstrumentDetails() {
          return details;
        });
        val = callback.call(context);
        if (end) {
          end();
        }
        return val;
      } else {
        return callback.call(context);
      }
    }
docs: Provides instrumentation for node managers.
  
  Wrap your node manager's render and re-render methods
  with this function.
  
  @param {Object} component Component or View instance (optional).
  @param {Function} callback The function to instrument.
  @param {Object} context The context to call the function with.
  @return {Object} Return value from the invoked callback.
  @private