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: tag.rs
    path of file: ./repos/salvo/crates/oapi/src/openapi
    
    the code of the file until where you have to start completion: //! Implements [OpenAPI Tag Object][tag] types.
//!
//! [tag]: https://spec.openapis.org/oas/latest.html#tag-object
use std::cmp::{Ord, Ordering, PartialOrd};
use std::collections::HashMap;

use serde::{Deserialize, Serialize};

use su
    
    fn tag_new() {
        let tag = Tag::new("tag name");
        assert_eq!(tag.name, "tag name");
        assert!(tag.description.is_none());
        assert!(tag.external_docs.is_none());
        assert!(tag.extensions.is_none());

        let tag = tag.name("new tag name");
        assert_eq!(tag.name, "new tag name");

        let tag = tag.description("description");
        assert!(tag.description.is_some());

        let tag = tag.external_docs(ExternalDocs::new(""));
        assert!(tag.external_docs.is_some());
    }