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: mod_file.rs
    path of file: ./repos/rusty-gql/cli/src/code_generate
    
    the code of the file until where you have to start completion: use heck::ToSnakeCase;
use tokio::io::AsyncWriteExt;

use super::{path_str, CreateFile};

pub struct ModFile<'a> {
    pub str
    
    fn content(&self) -> String {
        let mut mod_str = String::from("");
        let mut pub_use_str = String::from("");
        for name in &self.struct_names {
            let filename = &name.to_snake_case();
            mod_str += format!("mod {};\n", &filename).as_str();
            pub_use_str += format!("pub use {}::{};\n", &filename, &name).as_str();
        }

        format!("{}\n{}", mod_str, pub_use_str)
    }