1·To illustrate, Figure 5 shows the state of a hypothetical iterator that can move back one, two, three, or four places, but no more, because that would require accessing the previously visited leaf.
为了说明这个作法，图5显示一个虚构的迭代器的状态，它能够向后移动一、二、三、四个位置，但不能移动更多位置，因为这要求访问前面访问的叶节点。
2·But this much effort should really not be necessary; indexing and slicing should "just work" whether a concrete sequence or a iterator is involved.
但是，费这么大力气实际上应该是不必要的；无论涉及的是序列还是迭代器，编制索引和切片都应该是“可行的”。
3·Since it is implemented as an anonymous function within another function, one could do some preliminary checks and calculations before creating the iterator.
由于它是在另外一个函数当中实现了一个匿名函数，人们就能够做一些前置检查和在迭代器创建之后进行计算。
4·Since the first spatial iterator named outer encompasses both panes AL0 and AL1, the first digit following the pane name is a grouping digit for a branch in the tree.
由于命名靠外的第一个空间迭代器同时包含窗格al0和AL1，所以窗格名称后面的第一个数字是树中一个分支的组数字。
5·These work the same as the other iterator classes in PHP, but they are specially designed for certain instances.
它们与php中的其他迭代器类使用相同的工作方式，但是它们分别针对不同的情况。