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: format_push_string.rs
    path of file: ./repos/rust-clippy/tests/ui
    
    the code of the file until where you have to start completion: #![warn(clippy::format_push_string)]

fn main() {
    let mut string = String::new();
    string += &format!("{:?}", 1234);
    //~^ ERROR: `format!(..)` appended to existing `String`
    string.push_str(&format!("{:?}", 5678));
    //~^ ERROR: `format!(..)` appended to existing `String`
}

mod issue9493 {
    pub fn u8vec_to_hex(vector: &Vec<u8>, upper: bool) -> String {
        let mut hex = String::w
    
    pub fn other_cases() {
        let mut s = String::new();
        // if let
        s += &(if let Some(_a) = Some(1234) {
            //~^ ERROR: `format!(..)` appended to existing `String`
            format!("{}", 1234)
        } else {
            format!("{}", 1234)
        });
        // match
        s += &(match Some(1234) {
            //~^ ERROR: `format!(..)` appended to existing `String`
            Some(_) => format!("{}", 1234),
            None => format!("{}", 1234),
        });
    }