/store/book/author $.store.book[*].author the authors of all books in the store
//author $..author all authors
/store/* $.store.* all things in store, which are some books and a red bicycle.
/store//price $.store..price the price of everything in the store.
//book[3] $..book[2] the third book
//book[last()] $..book[(@.length-1)]
$..book[-1:] the last book in order.
//book[position()<3] $..book[0,1]
$..book[:2] the first two books
//book[isbn] $..book[?(@.isbn)] filter all books with isbn number
//book[price<10] $..book[?(@.price<10)] filter all books cheapier than 10
//* $..* all Elements in XML document. All members of JSON structure.
S. Keidel, W. Pfeiffer, and S. Erdweg. Proceedings of the 2016 ACM SIGPLAN International Conference on Software Language Engineering, page 152--162. ACM, (2016)