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: expand_field.rs
    path of file: ./repos/doku/doku-derive/src/expand
    
    the code of the file until where you have to start completion: use super::*;
use crate::attrs::DokuMetas;
use std::iter::FromIterator;

pub fn expand_field(
    field: &syn::Field,
    named: bool,
    rename_fields: RenameRule,
) -> Result<TokenStream2> {
    let syn::Field {
        attrs, ident, ty, ..
    } = field;

    let ident = ident
        .as_ref()
        .map(|ident| rename_fields.apply_to_field(&ident.to_string()));

    let mut field = Field {
        name: quote! { #ident },
        ty: quote! { #ty },
        metas: quote! { Default::default() },
        comment: quote! { None },
        example: quote! { None },
        aliases: quote! { &[] },
        tag: quote! { None },
        serializable: true,
        deserializable: true,
        flattened: false,
    };

    field.add_doc_attrs(attrs);
    field.add_s
    
    fn add_doku_attrs(&mut self, attrs: &[syn::Attribute]) -> Result<()> {
        let attrs::DokuField {
            as_,
            examples,
            metas,
            literal_example,
            flatten,
            rename,
            skip,
            tag,
        } = attrs::DokuField::from_ast(attrs)?;

        if let Some(val) = as_ {
            let val = string_to_path(&val)?;
            self.ty = quote! { #val };
        }

        if let Some(literal_example) = literal_example {
            self.example = quote! {
                Some(::doku::Example::Literal(#literal_example))
            };
        } else if !examples.is_empty() {
            self.example = quote! {
                Some(::doku::Example::from(&[#(#examples,)*][..]))
            };
        }

        if !metas.is_empty() {
            let metas = DokuMetas::from_iter(metas);

            let meta_keys = metas.metas.keys();
            let meta_values = metas.metas.values();

            self.metas = quote! {
                ::doku::Metas::default()
                #( .with(#meta_keys, #meta_values) )*
            };
        }

        if let Some(val) = flatten {
            self.flattened = val;
        }

        if let Some(val) = rename {
            self.name = quote_spanned! { val.span() => #val };
        }

        if let Some(val) = skip {
            self.serializable = !val;
            self.deserializable = !val;
        }

        if let Some(val) = tag {
            self.tag = quote! { Some(#val) };
        }

        Ok(())
    }