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: lib.rs
    path of file: ./repos/solang/tests/wasm_host_attr/src
    
    the code of the file until where you have to start completion: // SPDX-License-Identifier: Apache-2.0

use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;
use quote::{quote, ToTokens};
use syn::{ImplItem, ItemImpl, LitInt, Type};

struct HostFn {
    name: String,
    module: String,
    params: TokenStream2,
    block: TokenStream2,
    returns: TokenStream2,
}

impl
    
pub fn wasm_host(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let item = syn::parse_macro_input!(item as ItemImpl);
    let host_ty = item.self_ty; // Ignoring generics, we don't need them
    let impls = item
        .items
        .iter()
        .filter_map(HostFn::new)
        .map(|f| f.to_tokens(&host_ty));

    quote!(impl #host_ty {
        fn define(
            mut store: &mut ::wasmi::Store<#host_ty>,
            linker: &mut ::wasmi::Linker<#host_ty>
        ) {
            #( #impls )*
        }
    })
    .into()
}