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: test_parse_buffer.rs
    path of file: ./repos/phaser/phaser/vendor/syn/tests
    
    the code of the file until where you have to start completion: use proc_macro2::{Delimiter, Group, Punct, Spacing, TokenStream, TokenTree};
use std::iter::FromIterator;
use syn::parse::{discouraged::Speculative, Parse, ParseStream, Parser, Result};
use syn::{parenthesized, Token};

#[test]
#[should_panic(expected = "Fork was not derived from the advancing parse stream")]
fn smuggled_speculative_cursor_between_sources() {
    struct BreakRules;
    impl Parse for BreakRules {
        fn parse(input1: ParseStream) -> 
    
fn trailing_empty_none_group() {
    fn parse(input: ParseStream) -> Result<()> {
        input.parse::<Token![+]>()?;

        let content;
        parenthesized!(content in input);
        content.parse::<Token![+]>()?;

        Ok(())
    }

    // `+ ( + <Ø Ø> ) <Ø <Ø Ø> Ø>`
    let tokens = TokenStream::from_iter(vec![
        TokenTree::Punct(Punct::new('+', Spacing::Alone)),
        TokenTree::Group(Group::new(
            Delimiter::Parenthesis,
            TokenStream::from_iter(vec![
                TokenTree::Punct(Punct::new('+', Spacing::Alone)),
                TokenTree::Group(Group::new(Delimiter::None, TokenStream::new())),
            ]),
        )),
        TokenTree::Group(Group::new(Delimiter::None, TokenStream::new())),
        TokenTree::Group(Group::new(
            Delimiter::None,
            TokenStream::from_iter(vec![TokenTree::Group(Group::new(
                Delimiter::None,
                TokenStream::new(),
            ))]),
        )),
    ]);

    parse.parse2(tokens).unwrap();
}