Function fragment 

pub async fn fragment(
    uri: Option<Uri>,
    rp: Option<String>,
    a: Option<ArchiveId>,
    p: Option<String>,
    d: Option<String>,
    m: Option<String>,
    l: Option<Language>,
    e: Option<String>,
    s: Option<String>,
    context: Option<NarrativeUri>,
) -> Result<(Uri, Box<[Css]>, Box<str>), BackendError<ServerFnErrorErr>>