}
    /// Add a link line without a name to the document.
    pub fn link_unnamed(self, to: impl Into<String>) -> Self {
        let to = to.into();
        self.push(Doc::Link { to, name: None })

    }
    /// An iterator over references to the documents in the builder.
    pub fn iter(&self) -> impl Iterator<Item = &Doc> {
        self.docs.iter()
    }
    /// An iterator over mutable references to the documents in the builder.
    pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Doc> {
        self.docs.iter_mut()

impl IntoIterator for Builder {
    type Item = Doc;
    type IntoIter = std::vec::IntoIter<Doc>;

    fn into_iter(self) -> Self::IntoIter {
        self.docs.into_iter()
    }
}

    #[test]
    fn test_iter() {
        let expected = [
            Doc::Blank,
            Doc::Heading(Level::One, "Wow!".to_string()),
            Doc::Quote("Wee!".to_string()),
            Doc::Link {
                to: "gemini://foo.bar".to_string(),
                name: None,
            },
        ];
        let doc = Builder::new()
            .line()
            .h1("Wow!")
            .quote("Wee!")
            .link_unnamed("gemini://foo.bar");
        for (i, actual) in doc.iter().enumerate() {
            assert_eq!(actual, &expected[i])
        }
    }