getRange(id) {
    let range = this.ranges[id];

    if (range === undefined) {
      let node = this.nodes[id];

      if (node && node.bounds && isAttached(node.bounds)) {
        range = document.createRange();
        range.setStartBefore(node.bounds.firstNode);
        range.setEndAfter(node.bounds.lastNode);
      } else {
        // If the node has already been detached, we probably have a stale tree
        range = null;
      }

      this.ranges[id] = range;
    }

    return range;
  }
Get the DOM range for a give render node id.

@method getRange
@param {string} id A render node id.
@return {Option<Range>} The DOM range, if the render node is found and has valid `bounds`.