getInternalPath () {
    let node = this
    const internalPath = []
    while (node) {
      if (node.parent) {
        internalPath.unshift(node.getIndex())
      }
      node = node.parent
    }
    return internalPath
  }
Get the internal path of this node, a list with the child indexes.
@return {String[]} Array containing the internal path to this node