docs: function () {
      var self = this;
      if (! self.invalidated) {
        // if we're currently in _recompute(), don't enqueue
        // ourselves, since we'll rerun immediately anyway.
        if (! self._recomputing && ! self.stopped) {
          requireFlush();
          pendingComputations.push(this);
        }
  
        self.invalidated = true;
  
        // callbacks can't add callbacks, because
        // self.invalidated === true.
        for(var i = 0, f; f = self._onInvalidateCallbacks[i]; i++) {
          Deps.nonreactive(function () {
            callWithNoYieldsAllowed(f, self);
          });
        }
        self._onInvalidateCallbacks = [];
      }
    }