code: function fallbackResolve(path, root) {
    let steps = path.split("/")
    let node = root
    while (node) {
      let step = steps.shift()
      if (step === undefined) break
      if (step === '.') continue
      let [name, position] = step.split(/[\[\]]/)
      name = name.replace('_default_:', '')
      position = position ? parseInt(position) : 1
      node = findChild(node, name, position)
    }
    return node
  }
docs: Find a single node with XPath `path` using the simple, built-in evaluator.