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: example.rs
    path of file: ./repos/salvo/crates/oapi/src/openapi
    
    the code of the file until where you have to start completion: //! Implements [OpenAPI Example Object][example] can be used to define examples for [`Response`][response]s and
//! [`RequestBody`][request_body]s.
//!
//! [example]: https://spec.openapis.org/oas/latest.html#example-object
//! [response]: response/struct.Response.html
//! [request_body]: request_body/struct.RequestBody.html
use serde::{Deserialize, Serialize};

/// Implements [OpenAPI Example Object][example].
///
/// Example is used on path operations to describe possible response bodies.
///
/// [example]: https://spec
    
    fn test_example() {
        let example = Example::new();
        assert!(example.summary.is_empty());
        assert!(example.description.is_empty());
        assert!(example.value.is_none());
        assert!(example.external_value.is_empty());

        let example = example.summary("summary");
        assert!(example.summary == "summary");

        let example = example.description("description");
        assert!(example.description == "description");

        let example = example.external_value("external_value");
        assert!(example.external_value == "external_value");

        let example = example.value(serde_json::Value::String("value".to_string()));
        assert!(example.value.is_some());
        assert!(example.value.unwrap() == serde_json::Value::String("value".to_string()));
    }