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: built_in_tuple.rs
    path of file: ./repos/swift-bridge/crates/swift-bridge-ir/src/bridged_type
    
    the code of the file until where you have to start completion: use crate::bridged_type::shared_struct::UnnamedStructFields;
use crate::bridged_type::{
    BridgeableType, BuiltInResult, CFfiStruct, OnlyEncoding, TypePosition, UnusedOptionNoneValue,
};
use crate::parse::TypeDeclarations;
use crate::SWIFT_BRIDGE_PREFIX;
use std::fmt::Debug;

use proc_macro2::{Ident, Span, TokenStream};
use quote::{format_ident, quote, quote_spanned};
use syn::{Path, Type};

#[derive(Debug)]
pub(crate) struct BuiltInTuple(UnnamedStructFields);

impl BuiltInTuple {
    fn prefixed_ty_name(&self, types: &TypeDeclarations) -> Ident {
        let combined_types = self.0.combine_field_types_into_ffi_name_string(types);
        let ty_name = format_ident!("{}_{}", "tuple", combined_types);
        Ident::new(
            &format!("{}{}", SWIFT_BRIDGE_PREFIX, ty_name),
            ty_name.span(),
        )
    }

    /// Get the FFI compatib
    
    fn to_swift_type(&self, type_pos: TypePosition, types: &TypeDeclarations) -> String {
        match type_pos {
            TypePosition::FnArg(host_lang, _) => {
                if host_lang.is_swift() {
                    let field_signatures = self.0.combine_field_types_into_ffi_name_string(types);
                    format!("__swift_bridge__$tuple${field_signatures}")
                } else {
                    self.0.to_swift_tuple_signature(type_pos, types)
                }
            }
            TypePosition::FnReturn(host_lang) => {
                if host_lang.is_swift() {
                    let field_signatures = self.0.combine_field_types_into_ffi_name_string(types);
                    format!("__swift_bridge__$tuple${field_signatures}")
                } else {
                    self.0.to_swift_tuple_signature(type_pos, types)
                }
            }
            TypePosition::SharedStructField => todo!(),
            TypePosition::SwiftCallsRustAsyncOnCompleteReturnTy => todo!(),
        }
    }