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: output_exprs.rs
    path of file: ./repos/c2rust/c2rust-refactor/src/ast_manip
    
    the code of the file until where you have to start completion: //! `fold_output_exprs` function, for visiting return-value expressions.
use smallvec::SmallVec;
use syntax::ast::*;
use syntax::mut_visit::{sel
    
    fn flat_map_impl_item(&mut self, i: ImplItem) -> SmallVec<[ImplItem; 1]> {
        match i.kind {
            ImplItemKind::Method(..) => {
                self.with_trailing(true, |f| mut_visit::noop_flat_map_impl_item(i, f))
            }
            _ => mut_visit::noop_flat_map_impl_item(i, self),
        }
    }