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: fn_edit.rs
    path of file: ./repos/c2rust/c2rust-refactor/src/ast_manip
    
    the code of the file until where you have to start completion: //! Helpers for rewriting all `fn` itemlikes, regardless of item kind.
use smallvec::SmallVec;
use syntax::ast::*;
use syntax::mut_visit::{self, MutVisitor};
use syntax::ptr::P;
use syntax::util::map_in_place::MapInPlace;
use syntax::visit::{self, Visitor};
use syntax_pos::Span;
use smallvec::smallvec;

use crate::ast_manip::{AstName, GetNodeId, GetSpan, MutVisit, Visit};

/// Enum indicating which kind of itemlike a `fn` is.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum FnKind {
    Normal,
    ImplMethod,
    TraitMethod,
    Foreign,
}

/// Generic representation of a `fn`.
#[derive(Clone, Debug)]
pub struct FnLike {
    pub kind: FnKind,
    pub id: NodeId,
    pub ident: Ident,
    pub span: Span,
    pub decl: P<FnDecl>,
    pub block: Option<P<Block>>,
    pub attrs: Vec<Attribute>,
    // TODO: This should probably include `generics`, and maybe some kind of "parent generics" for
   
    
    fn flat_map_trait_item(&mut self, i: TraitItem) -> SmallVec<[TraitItem; 1]> {
        match i.kind {
            TraitItemKind::Method(..) => {}
            _ => return mut_visit::noop_flat_map_trait_item(i, self),
        }

        unpack!([i.kind] TraitItemKind::Method(sig, block));
        let FnSig { header, decl } = sig;
        let generics = i.generics;
        let vis = i.vis;

        let fl = FnLike {
            kind: FnKind::TraitMethod,
            id: i.id,
            ident: i.ident,
            span: i.span,
            decl,
            block,
            attrs: i.attrs,
        };
        let fls = (self.callback)(fl);

        fls.into_iter()
            .map(|fl| {
                let sig = FnSig {
                    header,
                    decl: fl.decl,
                };
                TraitItem {
                    id: fl.id,
                    ident: fl.ident,
                    span: fl.span,
                    vis: vis.clone(),
                    kind: TraitItemKind::Method(sig, fl.block),
                    attrs: fl.attrs,
                    generics: generics.clone(),
                    tokens: None,
                }
            })
            .flat_map(|i| mut_visit::noop_flat_map_trait_item(i, self))
            .collect()
    }