code: function (id) {
      var self = this;
      if (! self._published.has(id) && ! self._limit)
        throw Error("tried to remove something matching but not cached " + id);
  
      if (self._published.has(id)) {
        self._removePublished(id);
      } else if (self._unpublishedBuffer.has(id)) {
        self._removeBuffered(id);
      }
    }
docs: Called when a document leaves the "Matching" results set. Takes responsibility of keeping _unpublishedBuffer in sync with _published and the effect of limit enforced.