You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lib.rs
    path of file: ./repos/jsonpath-rs/src
    
    the code of the file until where you have to start completion: //! JSONPath implementation for Rust.
//!
//! The library is in development stage at the moment, but you can use already
//! limited functionality.
//!
//! Currently the following operators are supported:
//!
//! * `$` - The root element. All path expression should start with it.
//! * `.` - A direct child element.
//! * `..` - Any descendant element (aka deep child).
//!
//!
//! # Example
//!
//! ```
//! extern crate jsonpath;
//! extern crate serde_json;

    
//! fn main() {
//!     let jsondoc = r#"
//!         {
//!             "favorites": {
//!                "books": [
//!                    {
//!                        "title": "Der schwarze Obelist",
//!                        "author": "Erich Maria Remarque"
//!                    },
//!                    {
//!                        "title": "Le mur",
//!                        "author": "Jean-Paul Sartre"
//!                    }
//!                ]
//!             }
//!         }
//!     "#;
//!
//!     // Parse JSON document
//!     let json: Value = serde_json::from_str(jsondoc).unwrap();
//!
//!     // Create a JSONPath selector
//!     let selector = Selector::new("$.favorites.books.*.title").unwrap();
//!
//!     // Apply the selector to the JSON and convert Vec<&Value> into Vec<&str>
//!     let titles: Vec<&str> = selector.find(&json)
//!         .map(|t| t.as_str().unwrap())
//!         .collect();
//!     assert_eq!(titles, vec!["Der schwarze Obelist", "Le mur"]);
//! }