A first glance at the index might have you wondering about the title.
粗略的游览一下索引就会知道它的标题。
2
If there is no first item, or if the first item does not have a title, this item is treated the same as any other out-of-bounds index in a PHP array.
如果没有第一项，或者第一项没有标题，该项就按照常规php数组索引越界处理。
3
Genetic marking is the equivalent of giving every book a title, table of contents and index-and with much greater speed and accuracy than any librarian could manage.