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: spanned.rs
    path of file: ./repos/phaser/phaser/vendor/quote/src
    
    the code of the file until where you have to start completion: use crate::ToTokens;
use proc_macro2::{Span, TokenStream};

pub trait Spanned {
    fn __span(&self) -> Span;
}

impl Spanned for Span {
    fn __span(&self) -> Span {
        *self
    }
}

impl<T: ?Sized + ToTokens> Spanned for T {
    fn __span(&self) -> Span {
        join_spans(self.into_token_stream())
    }
}

fn join_spans(tokens: TokenStream) -> Span {
    let mut iter = tokens.into_iter().filter_map(|tt| {
        // FIXME: This shouldn't be required, since optimally spans should
        // never be invalid. This filter_map can probably be removed when
        // https://github.com/rust-lang/rust/issues
    
fn join_spans(tokens: TokenStream) -> Span {
    let mut iter = tokens.into_iter().filter_map(|tt| {
        // FIXME: This shouldn't be required, since optimally spans should
        // never be invalid. This filter_map can probably be removed when
        // https://github.com/rust-lang/rust/issues/43081 is resolved.
        let span = tt.span();
        let debug = format!("{:?}", span);
        if debug.ends_with("bytes(0..0)") {
            None
        } else {
            Some(span)
        }
    });

    let first = match iter.next() {
        Some(span) => span,
        None => return Span::call_site(),
    };

    iter.fold(None, |_prev, next| Some(next))
        .and_then(|last| first.join(last))
        .unwrap_or(first)
}