code: function validatePath (path, target) {
    var i = 0
    var len = path.length
    var ref = target
    for (; i < len; i++) {
      if (Iterable.isIterable(ref)) {
        ref = ref.getIn(path.slice(0, i))
        if (Iterable.isIndexed(ref) && !validateIndexToken(path[i])) {
          throw new error.PointerError('Invalid array index: ' + path[i])
        }
      }
    }
  }
docs: Validate key path
  
  @private
  @param {array} path
  @param {Immutable} target
  @throws PatchError