use proc_macro2::{Group, TokenStream, TokenTree}; pub(crate) fn sync(input: TokenStream) -> TokenStream {    let mut output = TokenStream::new();    let mut tokens = input.into_iter().peekable();     while let Some(token) = tokens.next() {        match token {            TokenTree::Group(group) => {                let mut replacement = Group::new(group.delimiter(), sync(group.stream()));                replacement.set_span(group.span());                output.extend([TokenTree::Group(replacement)]);            }            TokenTree::Ident(ident) if ident == "async" => {                if matches!(tokens.peek(), Some(TokenTree::Ident(ident)) if ident == "move") {                    let move_token = tokens.next();                    if matches!(tokens.peek(), Some(TokenTree::Punct(punct)) if punct.as_char() == '|') {                        output.extend(move_token);                    }                }            }            TokenTree::Punct(punct)                if punct.as_char() == '.'                    && matches!(tokens.peek(), Some(TokenTree::Ident(ident)) if ident == "await") =>            {                tokens.next();            }            token => output.extend([token]),        }    }    output}